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Merge pull request #45174 from ClickHouse/make-queries-copyable-from-docs
make more SQL queries copyable from docs in one click
This commit is contained in:
Sergei Trifonov
GitHub
commit
ec9f10e934
@ -101,7 +101,7 @@ The `TabSeparated` format supports outputting total values (when using WITH TOTA
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SELECT EventDate, count() AS c FROM test.hits GROUP BY EventDate WITH TOTALS ORDER BY EventDate FORMAT TabSeparated
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```
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``` text
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``` response
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2014-03-17 1406958
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2014-03-18 1383658
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2014-03-19 1405797
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@ -177,7 +177,7 @@ INSERT INTO nestedt Values ( 1, [1], ['a'])
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SELECT * FROM nestedt FORMAT TSV
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```
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``` text
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``` response
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1 [1] ['a']
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```
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@ -761,7 +761,7 @@ SELECT * FROM json_as_string;
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Result:
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``` text
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``` response
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┌─json──────────────────────────────┐
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│ {"foo":{"bar":{"x":"y"},"baz":1}} │
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│ {} │
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@ -782,7 +782,7 @@ SELECT * FROM json_square_brackets;
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Result:
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```text
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```response
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┌─field──────────────────────┐
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│ {"id": 1, "name": "name1"} │
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│ {"id": 2, "name": "name2"} │
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@ -1118,7 +1118,7 @@ When inserting data with `input_format_defaults_for_omitted_fields = 1`, ClickHo
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Consider the `UserActivity` table as an example:
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``` text
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``` response
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┌──────────────UserID─┬─PageViews─┬─Duration─┬─Sign─┐
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│ 4324182021466249494 │ 5 │ 146 │ -1 │
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│ 4324182021466249494 │ 6 │ 185 │ 1 │
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@ -1127,7 +1127,7 @@ Consider the `UserActivity` table as an example:
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The query `SELECT * FROM UserActivity FORMAT JSONEachRow` returns:
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``` text
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``` response
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{"UserID":"4324182021466249494","PageViews":5,"Duration":146,"Sign":-1}
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{"UserID":"4324182021466249494","PageViews":6,"Duration":185,"Sign":1}
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```
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@ -1171,7 +1171,7 @@ Without this setting, ClickHouse throws an exception.
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SELECT name, value FROM system.settings WHERE name = 'input_format_import_nested_json'
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```
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``` text
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``` response
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┌─name────────────────────────────┬─value─┐
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│ input_format_import_nested_json │ 0 │
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└─────────────────────────────────┴───────┘
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@ -1181,7 +1181,7 @@ SELECT name, value FROM system.settings WHERE name = 'input_format_import_nested
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INSERT INTO json_each_row_nested FORMAT JSONEachRow {"n": {"s": ["abc", "def"], "i": [1, 23]}}
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```
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``` text
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``` response
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Code: 117. DB::Exception: Unknown field found while parsing JSONEachRow format: n: (at row 1)
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```
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@ -1191,7 +1191,7 @@ INSERT INTO json_each_row_nested FORMAT JSONEachRow {"n": {"s": ["abc", "def"],
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SELECT * FROM json_each_row_nested
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```
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``` text
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``` response
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┌─n.s───────────┬─n.i────┐
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│ ['abc','def'] │ [1,23] │
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└───────────────┴────────┘
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@ -1265,7 +1265,7 @@ For input it uses the following correspondence between BSON types and ClickHouse
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| `\x10` int32 | [Int32/UInt32](/docs/en/sql-reference/data-types/int-uint.md)/[Decimal32](/docs/en/sql-reference/data-types/decimal.md) |
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| `\x12` int64 | [Int64/UInt64](/docs/en/sql-reference/data-types/int-uint.md)/[Decimal64](/docs/en/sql-reference/data-types/decimal.md)/[DateTime64](/docs/en/sql-reference/data-types/datetime64.md) |
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Other BSON types are not supported. Also, it performs conversion between different integer types (for example, you can insert BSON int32 value into ClickHouse UInt8).
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Other BSON types are not supported. Also, it performs conversion between different integer types (for example, you can insert BSON int32 value into ClickHouse UInt8).
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Big integers and decimals (Int128/UInt128/Int256/UInt256/Decimal128/Decimal256) can be parsed from BSON Binary value with `\x00` binary subtype. In this case this format will validate that the size of binary data equals the size of expected value.
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Note: this format don't work properly on Big-Endian platforms.
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@ -1300,7 +1300,7 @@ Example (shown for the [PrettyCompact](#prettycompact) format):
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SELECT * FROM t_null
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```
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``` text
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``` response
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┌─x─┬────y─┐
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│ 1 │ ᴺᵁᴸᴸ │
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└───┴──────┘
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@ -1312,7 +1312,7 @@ Rows are not escaped in Pretty\* formats. Example is shown for the [PrettyCompac
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SELECT 'String with \'quotes\' and \t character' AS Escaping_test
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```
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``` text
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``` response
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┌─Escaping_test────────────────────────┐
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│ String with 'quotes' and character │
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└──────────────────────────────────────┘
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@ -1327,7 +1327,7 @@ The Pretty format supports outputting total values (when using WITH TOTALS) and
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SELECT EventDate, count() AS c FROM test.hits GROUP BY EventDate WITH TOTALS ORDER BY EventDate FORMAT PrettyCompact
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```
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``` text
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``` response
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┌──EventDate─┬───────c─┐
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│ 2014-03-17 │ 1406958 │
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│ 2014-03-18 │ 1383658 │
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@ -1488,7 +1488,7 @@ Example:
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SELECT * FROM t_null FORMAT Vertical
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```
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``` text
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``` response
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Row 1:
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──────
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x: 1
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@ -1501,7 +1501,7 @@ Rows are not escaped in Vertical format:
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SELECT 'string with \'quotes\' and \t with some special \n characters' AS test FORMAT Vertical
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```
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``` text
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``` response
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Row 1:
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──────
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test: string with 'quotes' and with some special
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@ -2319,25 +2319,22 @@ INSERT INTO `test2` VALUES (1),(2),(3);
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Queries:
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```sql
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:) desc file(dump.sql, MySQLDump) settings input_format_mysql_dump_table_name='test2'
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DESCRIBE TABLE file(dump.sql, MySQLDump)
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SETTINGS input_format_mysql_dump_table_name = 'test2'
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Query id: 25e66c89-e10a-42a8-9b42-1ee8bbbde5ef
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DESCRIBE TABLE file(dump.sql, MySQLDump) SETTINGS input_format_mysql_dump_table_name = 'test2'
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```
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```text
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┌─name─┬─type────────────┬─default_type─┬─default_expression─┬─comment─┬─codec_expression─┬─ttl_expression─┐
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│ x │ Nullable(Int32) │ │ │ │ │ │
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└──────┴─────────────────┴──────────────┴────────────────────┴─────────┴──────────────────┴────────────────┘
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```
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:) select * from file(dump.sql, MySQLDump) settings input_format_mysql_dump_table_name='test2'
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```sql
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SELECT *
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FROM file(dump.sql, MySQLDump)
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SETTINGS input_format_mysql_dump_table_name = 'test2'
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```
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Query id: 17d59664-ebce-4053-bb79-d46a516fb590
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```text
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┌─x─┐
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│ 1 │
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│ 2 │
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@ -17,10 +17,10 @@ Columns:
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**Example**
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```sql
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:) SELECT * FROM system.disks;
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SELECT * FROM system.disks;
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```
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```text
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```response
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┌─name────┬─path─────────────────┬───free_space─┬──total_space─┬─keep_free_space─┐
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│ default │ /var/lib/clickhouse/ │ 276392587264 │ 490652508160 │ 0 │
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└─────────┴──────────────────────┴──────────────┴──────────────┴─────────────────┘
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@ -15,10 +15,10 @@ Columns:
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**Example**
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```sql
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:) SELECT * FROM system.merge_tree_settings LIMIT 4 FORMAT Vertical;
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SELECT * FROM system.merge_tree_settings LIMIT 4 FORMAT Vertical;
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```
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```text
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```response
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Row 1:
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──────
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name: index_granularity
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@ -12,10 +12,10 @@ Reads from this table are not parallelized.
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**Example**
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```sql
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:) SELECT * FROM system.numbers LIMIT 10;
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SELECT * FROM system.numbers LIMIT 10;
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```
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```text
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```response
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┌─number─┐
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│ 0 │
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│ 1 │
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@ -10,10 +10,10 @@ Used for tests.
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**Example**
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```sql
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:) SELECT * FROM system.numbers_mt LIMIT 10;
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SELECT * FROM system.numbers_mt LIMIT 10;
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```
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```text
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```response
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┌─number─┐
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│ 0 │
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│ 1 │
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@ -12,10 +12,10 @@ This is similar to the `DUAL` table found in other DBMSs.
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**Example**
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```sql
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:) SELECT * FROM system.one LIMIT 10;
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SELECT * FROM system.one LIMIT 10;
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```
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```text
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```response
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┌─dummy─┐
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│ 0 │
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└───────┘
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@ -20,10 +20,10 @@ Columns:
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- `is_all_data_sent` (Int8) – Was all data sent to the client (in other words query had been finished on the server).
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```sql
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:) SELECT * FROM system.processes LIMIT 10 FORMAT Vertical;
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SELECT * FROM system.processes LIMIT 10 FORMAT Vertical;
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```
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```text
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```response
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Row 1:
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──────
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is_initial_query: 1
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@ -27,7 +27,7 @@ A table with data parsed from `data` argument according specified format and ext
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**Query:**
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``` sql
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:) select * from format(JSONEachRow,
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SELECT * FROM format(JSONEachRow,
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$$
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{"a": "Hello", "b": 111}
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{"a": "World", "b": 123}
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@ -38,7 +38,7 @@ $$)
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**Result:**
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```text
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```response
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┌───b─┬─a─────┐
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│ 111 │ Hello │
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│ 123 │ World │
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@ -49,8 +49,7 @@ $$)
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**Query:**
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```sql
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:) desc format(JSONEachRow,
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DESC format(JSONEachRow,
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$$
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{"a": "Hello", "b": 111}
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{"a": "World", "b": 123}
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@ -61,7 +60,7 @@ $$)
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**Result:**
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```text
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```response
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┌─name─┬─type──────────────┬─default_type─┬─default_expression─┬─comment─┬─codec_expression─┬─ttl_expression─┐
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│ b │ Nullable(Float64) │ │ │ │ │ │
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│ a │ Nullable(String) │ │ │ │ │ │
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@ -27,7 +27,7 @@ A table with data parsed from `data` argument according specified format and ext
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|
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**Query:**
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``` sql
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:) select * from format(JSONEachRow,
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SELECT * FROM format(JSONEachRow,
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$$
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{"a": "Hello", "b": 111}
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{"a": "World", "b": 123}
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@ -38,7 +38,7 @@ $$)
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**Result:**
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```text
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```response
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┌───b─┬─a─────┐
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│ 111 │ Hello │
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│ 123 │ World │
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@ -49,8 +49,7 @@ $$)
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**Query:**
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```sql
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:) desc format(JSONEachRow,
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DESC format(JSONEachRow,
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$$
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{"a": "Hello", "b": 111}
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{"a": "World", "b": 123}
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@ -61,7 +60,7 @@ $$)
|
||||
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**Result:**
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```text
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```response
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┌─name─┬─type──────────────┬─default_type─┬─default_expression─┬─comment─┬─codec_expression─┬─ttl_expression─┐
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│ b │ Nullable(Float64) │ │ │ │ │ │
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│ a │ Nullable(String) │ │ │ │ │ │
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@ -69,7 +69,9 @@ ORDER BY key
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向其中插入数据：
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:) INSERT INTO summtt Values(1,1),(1,2),(2,1)
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``` sql
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INSERT INTO summtt Values(1,1),(1,2),(2,1)
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```
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ClickHouse可能不会完整的汇总所有行（[见下文](#data-processing)）,因此我们在查询中使用了聚合函数 `sum` 和 `GROUP BY` 子句。
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@ -16,7 +16,7 @@ slug: /zh/operations/system-tables/disks
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**示例**
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```sql
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:) SELECT * FROM system.disks;
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SELECT * FROM system.disks;
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```
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```text
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@ -16,10 +16,10 @@ slug: /zh/operations/system-tables/merge_tree_settings
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**示例**
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```sql
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:) SELECT * FROM system.merge_tree_settings LIMIT 4 FORMAT Vertical;
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SELECT * FROM system.merge_tree_settings LIMIT 4 FORMAT Vertical;
|
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```
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||||
|
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```text
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```response
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Row 1:
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──────
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name: index_granularity
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||||
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@ -12,10 +12,10 @@ slug: /zh/operations/system-tables/numbers
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**示例**
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|
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```sql
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:) SELECT * FROM system.numbers LIMIT 10;
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SELECT * FROM system.numbers LIMIT 10;
|
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```
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||||
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```text
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```response
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┌─number─┐
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│ 0 │
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│ 1 │
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||||
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||||
@ -12,10 +12,10 @@ slug: /zh/operations/system-tables/one
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**示例**
|
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|
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```sql
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:) SELECT * FROM system.one LIMIT 10;
|
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SELECT * FROM system.one LIMIT 10;
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||||
```
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||||
|
||||
```text
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||||
```response
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||||
┌─dummy─┐
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│ 0 │
|
||||
└───────┘
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||||
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||||
@ -19,29 +19,25 @@ slug: /zh/sql-reference/data-types/array
|
||||
|
||||
创建数组示例：
|
||||
|
||||
:) SELECT array(1, 2) AS x, toTypeName(x)
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||||
```sql
|
||||
SELECT array(1, 2) AS x, toTypeName(x)
|
||||
```
|
||||
|
||||
SELECT
|
||||
[1, 2] AS x,
|
||||
toTypeName(x)
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||||
```response
|
||||
┌─x─────┬─toTypeName(array(1, 2))─┐
|
||||
│ [1,2] │ Array(UInt8) │
|
||||
└───────┴─────────────────────────┘
|
||||
```
|
||||
|
||||
┌─x─────┬─toTypeName(array(1, 2))─┐
|
||||
│ [1,2] │ Array(UInt8) │
|
||||
└───────┴─────────────────────────┘
|
||||
``` sql
|
||||
SELECT [1, 2] AS x, toTypeName(x)
|
||||
```
|
||||
|
||||
1 rows in set. Elapsed: 0.002 sec.
|
||||
|
||||
:) SELECT [1, 2] AS x, toTypeName(x)
|
||||
|
||||
SELECT
|
||||
[1, 2] AS x,
|
||||
toTypeName(x)
|
||||
|
||||
┌─x─────┬─toTypeName([1, 2])─┐
|
||||
│ [1,2] │ Array(UInt8) │
|
||||
└───────┴────────────────────┘
|
||||
|
||||
1 rows in set. Elapsed: 0.002 sec.
|
||||
```response
|
||||
┌─x─────┬─toTypeName([1, 2])─┐
|
||||
│ [1,2] │ Array(UInt8) │
|
||||
└───────┴────────────────────┘
|
||||
```
|
||||
|
||||
## 使用数据类型 {#shi-yong-shu-ju-lei-xing}
|
||||
|
||||
@ -50,26 +46,23 @@ ClickHouse会自动检测数组元素,并根据元素计算出存储这些元素
|
||||
如果 ClickHouse 无法确定数据类型，它将产生异常。当尝试同时创建一个包含字符串和数字的数组时会发生这种情况 (`SELECT array(1, 'a')`)。
|
||||
|
||||
自动数据类型检测示例：
|
||||
```sql
|
||||
SELECT array(1, 2, NULL) AS x, toTypeName(x)
|
||||
```
|
||||
|
||||
:) SELECT array(1, 2, NULL) AS x, toTypeName(x)
|
||||
|
||||
SELECT
|
||||
[1, 2, NULL] AS x,
|
||||
toTypeName(x)
|
||||
|
||||
┌─x──────────┬─toTypeName(array(1, 2, NULL))─┐
|
||||
│ [1,2,NULL] │ Array(Nullable(UInt8)) │
|
||||
└────────────┴───────────────────────────────┘
|
||||
|
||||
1 rows in set. Elapsed: 0.002 sec.
|
||||
```response
|
||||
┌─x──────────┬─toTypeName(array(1, 2, NULL))─┐
|
||||
│ [1,2,NULL] │ Array(Nullable(UInt8)) │
|
||||
└────────────┴───────────────────────────────┘
|
||||
```
|
||||
|
||||
如果您尝试创建不兼容的数据类型数组，ClickHouse 将引发异常：
|
||||
|
||||
:) SELECT array(1, 'a')
|
||||
```sql
|
||||
SELECT array(1, 'a')
|
||||
```
|
||||
|
||||
SELECT [1, 'a']
|
||||
|
||||
Received exception from server (version 1.1.54388):
|
||||
Code: 386. DB::Exception: Received from localhost:9000, 127.0.0.1. DB::Exception: There is no supertype for types UInt8, String because some of them are String/FixedString and some of them are not.
|
||||
|
||||
0 rows in set. Elapsed: 0.246 sec.
|
||||
```response
|
||||
Received exception from server (version 1.1.54388):
|
||||
Code: 386. DB::Exception: Received from localhost:9000, 127.0.0.1. DB::Exception: There is no supertype for types UInt8, String because some of them are String/FixedString and some of them are not.
|
||||
```
|
||||
|
||||
@ -20,49 +20,64 @@ slug: /zh/sql-reference/data-types/enum
|
||||
|
||||
这个 `x` 列只能存储类型定义中列出的值：`'hello'`或`'world'`。如果您尝试保存任何其他值，ClickHouse 抛出异常。
|
||||
|
||||
:) INSERT INTO t_enum VALUES ('hello'), ('world'), ('hello')
|
||||
```sql
|
||||
INSERT INTO t_enum VALUES ('hello'), ('world'), ('hello')
|
||||
```
|
||||
|
||||
INSERT INTO t_enum VALUES
|
||||
```response
|
||||
Ok.
|
||||
|
||||
Ok.
|
||||
3 rows in set. Elapsed: 0.002 sec.
|
||||
```
|
||||
|
||||
3 rows in set. Elapsed: 0.002 sec.
|
||||
```sql
|
||||
INSERT INTO t_enum VALUES('a')
|
||||
```
|
||||
|
||||
:) insert into t_enum values('a')
|
||||
|
||||
INSERT INTO t_enum VALUES
|
||||
|
||||
|
||||
Exception on client:
|
||||
Code: 49. DB::Exception: Unknown element 'a' for type Enum8('hello' = 1, 'world' = 2)
|
||||
```response
|
||||
Exception on client:
|
||||
Code: 49. DB::Exception: Unknown element 'a' for type Enum8('hello' = 1, 'world' = 2)
|
||||
```
|
||||
|
||||
当您从表中查询数据时，ClickHouse 从 `Enum` 中输出字符串值。
|
||||
|
||||
SELECT * FROM t_enum
|
||||
```sql
|
||||
SELECT * FROM t_enum
|
||||
```
|
||||
|
||||
┌─x─────┐
|
||||
│ hello │
|
||||
│ world │
|
||||
│ hello │
|
||||
└───────┘
|
||||
```response
|
||||
┌─x─────┐
|
||||
│ hello │
|
||||
│ world │
|
||||
│ hello │
|
||||
└───────┘
|
||||
```
|
||||
|
||||
如果需要看到对应行的数值，则必须将 `Enum` 值转换为整数类型。
|
||||
|
||||
SELECT CAST(x, 'Int8') FROM t_enum
|
||||
```sql
|
||||
SELECT CAST(x, 'Int8') FROM t_enum
|
||||
```
|
||||
|
||||
┌─CAST(x, 'Int8')─┐
|
||||
│ 1 │
|
||||
│ 2 │
|
||||
│ 1 │
|
||||
└─────────────────┘
|
||||
```response
|
||||
┌─CAST(x, 'Int8')─┐
|
||||
│ 1 │
|
||||
│ 2 │
|
||||
│ 1 │
|
||||
└─────────────────┘
|
||||
```
|
||||
|
||||
在查询中创建枚举值，您还需要使用 `CAST`。
|
||||
|
||||
SELECT toTypeName(CAST('a', 'Enum8(\'a\' = 1, \'b\' = 2)'))
|
||||
```sql
|
||||
SELECT toTypeName(CAST('a', 'Enum8(\'a\' = 1, \'b\' = 2)'))
|
||||
```
|
||||
|
||||
┌─toTypeName(CAST('a', 'Enum8(\'a\' = 1, \'b\' = 2)'))─┐
|
||||
│ Enum8('a' = 1, 'b' = 2) │
|
||||
└──────────────────────────────────────────────────────┘
|
||||
```response
|
||||
┌─toTypeName(CAST('a', 'Enum8(\'a\' = 1, \'b\' = 2)'))─┐
|
||||
│ Enum8('a' = 1, 'b' = 2) │
|
||||
└──────────────────────────────────────────────────────┘
|
||||
```
|
||||
|
||||
## 规则及用法 {#gui-ze-ji-yong-fa}
|
||||
|
||||
@ -72,15 +87,19 @@ slug: /zh/sql-reference/data-types/enum
|
||||
|
||||
`Enum` 包含在 [可为空](nullable.md) 类型中。因此，如果您使用此查询创建一个表
|
||||
|
||||
CREATE TABLE t_enum_nullable
|
||||
(
|
||||
x Nullable( Enum8('hello' = 1, 'world' = 2) )
|
||||
)
|
||||
ENGINE = TinyLog
|
||||
```sql
|
||||
CREATE TABLE t_enum_nullable
|
||||
(
|
||||
x Nullable( Enum8('hello' = 1, 'world' = 2) )
|
||||
)
|
||||
ENGINE = TinyLog
|
||||
```
|
||||
|
||||
不仅可以存储 `'hello'` 和 `'world'` ，还可以存储 `NULL`。
|
||||
|
||||
INSERT INTO t_enum_nullable Values('hello'),('world'),(NULL)
|
||||
```sql
|
||||
INSERT INTO t_enum_nullable Values('hello'),('world'),(NULL)
|
||||
```
|
||||
|
||||
在内存中，`Enum` 列的存储方式与相应数值的 `Int8` 或 `Int16` 相同。
|
||||
|
||||
|
||||
@ -9,11 +9,11 @@ slug: /zh/sql-reference/data-types/special-data-types/nothing
|
||||
|
||||
`Nothing` 类型也可以用来表示空数组：
|
||||
|
||||
``` bash
|
||||
:) SELECT toTypeName(array())
|
||||
|
||||
SELECT toTypeName([])
|
||||
```sql
|
||||
SELECT toTypeName(array())
|
||||
```
|
||||
|
||||
```response
|
||||
┌─toTypeName(array())─┐
|
||||
│ Array(Nothing) │
|
||||
└─────────────────────┘
|
||||
|
||||
@ -17,17 +17,15 @@ slug: /zh/sql-reference/data-types/tuple
|
||||
|
||||
创建元组的示例：
|
||||
|
||||
:) SELECT tuple(1,'a') AS x, toTypeName(x)
|
||||
```sql
|
||||
SELECT tuple(1,'a') AS x, toTypeName(x)
|
||||
```
|
||||
|
||||
SELECT
|
||||
(1, 'a') AS x,
|
||||
toTypeName(x)
|
||||
|
||||
┌─x───────┬─toTypeName(tuple(1, 'a'))─┐
|
||||
│ (1,'a') │ Tuple(UInt8, String) │
|
||||
└─────────┴───────────────────────────┘
|
||||
|
||||
1 rows in set. Elapsed: 0.021 sec.
|
||||
```response
|
||||
┌─x───────┬─toTypeName(tuple(1, 'a'))─┐
|
||||
│ (1,'a') │ Tuple(UInt8, String) │
|
||||
└─────────┴───────────────────────────┘
|
||||
```
|
||||
|
||||
## 元组中的数据类型 {#yuan-zu-zhong-de-shu-ju-lei-xing}
|
||||
|
||||
@ -35,14 +33,12 @@ slug: /zh/sql-reference/data-types/tuple
|
||||
|
||||
自动数据类型检测示例：
|
||||
|
||||
SELECT tuple(1, NULL) AS x, toTypeName(x)
|
||||
```sql
|
||||
SELECT tuple(1, NULL) AS x, toTypeName(x)
|
||||
```
|
||||
|
||||
SELECT
|
||||
(1, NULL) AS x,
|
||||
toTypeName(x)
|
||||
|
||||
┌─x────────┬─toTypeName(tuple(1, NULL))──────┐
|
||||
│ (1,NULL) │ Tuple(UInt8, Nullable(Nothing)) │
|
||||
└──────────┴─────────────────────────────────┘
|
||||
|
||||
1 rows in set. Elapsed: 0.002 sec.
|
||||
```response
|
||||
┌─x────────┬─toTypeName(tuple(1, NULL))──────┐
|
||||
│ (1,NULL) │ Tuple(UInt8, Nullable(Nothing)) │
|
||||
└──────────┴─────────────────────────────────┘
|
||||
```
|
||||
|
||||
@ -22,24 +22,24 @@ slug: /zh/sql-reference/functions/functions-for-nulls
|
||||
|
||||
存在以下内容的表
|
||||
|
||||
┌─x─┬────y─┐
|
||||
│ 1 │ ᴺᵁᴸᴸ │
|
||||
│ 2 │ 3 │
|
||||
└───┴──────┘
|
||||
```response
|
||||
┌─x─┬────y─┐
|
||||
│ 1 │ ᴺᵁᴸᴸ │
|
||||
│ 2 │ 3 │
|
||||
└───┴──────┘
|
||||
```
|
||||
|
||||
对其进行查询
|
||||
|
||||
:) SELECT x FROM t_null WHERE isNull(y)
|
||||
```sql
|
||||
SELECT x FROM t_null WHERE isNull(y)
|
||||
```
|
||||
|
||||
SELECT x
|
||||
FROM t_null
|
||||
WHERE isNull(y)
|
||||
|
||||
┌─x─┐
|
||||
│ 1 │
|
||||
└───┘
|
||||
|
||||
1 rows in set. Elapsed: 0.010 sec.
|
||||
```response
|
||||
┌─x─┐
|
||||
│ 1 │
|
||||
└───┘
|
||||
```
|
||||
|
||||
## isNotNull {#isnotnull}
|
||||
|
||||
@ -60,24 +60,24 @@ slug: /zh/sql-reference/functions/functions-for-nulls
|
||||
|
||||
存在以下内容的表
|
||||
|
||||
┌─x─┬────y─┐
|
||||
│ 1 │ ᴺᵁᴸᴸ │
|
||||
│ 2 │ 3 │
|
||||
└───┴──────┘
|
||||
```response
|
||||
┌─x─┬────y─┐
|
||||
│ 1 │ ᴺᵁᴸᴸ │
|
||||
│ 2 │ 3 │
|
||||
└───┴──────┘
|
||||
```
|
||||
|
||||
对其进行查询
|
||||
|
||||
:) SELECT x FROM t_null WHERE isNotNull(y)
|
||||
```sql
|
||||
SELECT x FROM t_null WHERE isNotNull(y)
|
||||
```
|
||||
|
||||
SELECT x
|
||||
FROM t_null
|
||||
WHERE isNotNull(y)
|
||||
|
||||
┌─x─┐
|
||||
│ 2 │
|
||||
└───┘
|
||||
|
||||
1 rows in set. Elapsed: 0.010 sec.
|
||||
```response
|
||||
┌─x─┐
|
||||
│ 2 │
|
||||
└───┘
|
||||
```
|
||||
|
||||
## 合并 {#coalesce}
|
||||
|
||||
@ -98,26 +98,27 @@ slug: /zh/sql-reference/functions/functions-for-nulls
|
||||
|
||||
考虑可以指定多种联系客户的方式的联系人列表。
|
||||
|
||||
┌─name─────┬─mail─┬─phone─────┬──icq─┐
|
||||
│ client 1 │ ᴺᵁᴸᴸ │ 123-45-67 │ 123 │
|
||||
│ client 2 │ ᴺᵁᴸᴸ │ ᴺᵁᴸᴸ │ ᴺᵁᴸᴸ │
|
||||
└──────────┴──────┴───────────┴──────┘
|
||||
```response
|
||||
┌─name─────┬─mail─┬─phone─────┬──icq─┐
|
||||
│ client 1 │ ᴺᵁᴸᴸ │ 123-45-67 │ 123 │
|
||||
│ client 2 │ ᴺᵁᴸᴸ │ ᴺᵁᴸᴸ │ ᴺᵁᴸᴸ │
|
||||
└──────────┴──────┴───────────┴──────┘
|
||||
```
|
||||
|
||||
`mail`和`phone`字段是String类型，但`icq`字段是`UInt32`，所以它需要转换为`String`。
|
||||
|
||||
从联系人列表中获取客户的第一个可用联系方式：
|
||||
|
||||
:) SELECT coalesce(mail, phone, CAST(icq,'Nullable(String)')) FROM aBook
|
||||
```sql
|
||||
SELECT coalesce(mail, phone, CAST(icq,'Nullable(String)')) FROM aBook
|
||||
```
|
||||
|
||||
SELECT coalesce(mail, phone, CAST(icq, 'Nullable(String)'))
|
||||
FROM aBook
|
||||
|
||||
┌─name─────┬─coalesce(mail, phone, CAST(icq, 'Nullable(String)'))─┐
|
||||
│ client 1 │ 123-45-67 │
|
||||
│ client 2 │ ᴺᵁᴸᴸ │
|
||||
└──────────┴──────────────────────────────────────────────────────┘
|
||||
|
||||
2 rows in set. Elapsed: 0.006 sec.
|
||||
```response
|
||||
┌─name─────┬─coalesce(mail, phone, CAST(icq, 'Nullable(String)'))─┐
|
||||
│ client 1 │ 123-45-67 │
|
||||
│ client 2 │ ᴺᵁᴸᴸ │
|
||||
└──────────┴──────────────────────────────────────────────────────┘
|
||||
```
|
||||
|
||||
## ifNull {#ifnull}
|
||||
|
||||
|
||||
@ -33,7 +33,7 @@ slug: /zh/sql-reference/functions/other-functions
|
||||
SELECT 'some/long/path/to/file' AS a, basename(a)
|
||||
```
|
||||
|
||||
``` text
|
||||
```response
|
||||
┌─a──────────────────────┬─basename('some\\long\\path\\to\\file')─┐
|
||||
│ some\long\path\to\file │ file │
|
||||
└────────────────────────┴────────────────────────────────────────┘
|
||||
@ -43,7 +43,7 @@ SELECT 'some/long/path/to/file' AS a, basename(a)
|
||||
SELECT 'some\\long\\path\\to\\file' AS a, basename(a)
|
||||
```
|
||||
|
||||
``` text
|
||||
```response
|
||||
┌─a──────────────────────┬─basename('some\\long\\path\\to\\file')─┐
|
||||
│ some\long\path\to\file │ file │
|
||||
└────────────────────────┴────────────────────────────────────────┘
|
||||
@ -53,7 +53,7 @@ SELECT 'some\\long\\path\\to\\file' AS a, basename(a)
|
||||
SELECT 'some-file-name' AS a, basename(a)
|
||||
```
|
||||
|
||||
``` text
|
||||
```response
|
||||
┌─a──────────────┬─basename('some-file-name')─┐
|
||||
│ some-file-name │ some-file-name │
|
||||
└────────────────┴────────────────────────────┘
|
||||
@ -398,23 +398,25 @@ FROM
|
||||
|
||||
**`toTypeName ' 与 ' toColumnTypeName`的区别示例**
|
||||
|
||||
:) select toTypeName(cast('2018-01-01 01:02:03' AS DateTime))
|
||||
```sql
|
||||
SELECT toTypeName(CAST('2018-01-01 01:02:03', 'DateTime'))
|
||||
```
|
||||
|
||||
SELECT toTypeName(CAST('2018-01-01 01:02:03', 'DateTime'))
|
||||
```response
|
||||
┌─toTypeName(CAST('2018-01-01 01:02:03', 'DateTime'))─┐
|
||||
│ DateTime │
|
||||
└─────────────────────────────────────────────────────┘
|
||||
```
|
||||
|
||||
┌─toTypeName(CAST('2018-01-01 01:02:03', 'DateTime'))─┐
|
||||
│ DateTime │
|
||||
└─────────────────────────────────────────────────────┘
|
||||
```sql
|
||||
SELECT toColumnTypeName(CAST('2018-01-01 01:02:03', 'DateTime'))
|
||||
```
|
||||
|
||||
1 rows in set. Elapsed: 0.008 sec.
|
||||
|
||||
:) select toColumnTypeName(cast('2018-01-01 01:02:03' AS DateTime))
|
||||
|
||||
SELECT toColumnTypeName(CAST('2018-01-01 01:02:03', 'DateTime'))
|
||||
|
||||
┌─toColumnTypeName(CAST('2018-01-01 01:02:03', 'DateTime'))─┐
|
||||
│ Const(UInt32) │
|
||||
└───────────────────────────────────────────────────────────┘
|
||||
```response
|
||||
┌─toColumnTypeName(CAST('2018-01-01 01:02:03', 'DateTime'))─┐
|
||||
│ Const(UInt32) │
|
||||
└───────────────────────────────────────────────────────────┘
|
||||
```
|
||||
|
||||
该示例显示`DateTime`数据类型作为`Const(UInt32)`存储在内存中。
|
||||
|
||||
@ -460,26 +462,25 @@ FROM
|
||||
|
||||
**示例**
|
||||
|
||||
:) SELECT defaultValueOfArgumentType( CAST(1 AS Int8) )
|
||||
```sql
|
||||
SELECT defaultValueOfArgumentType(CAST(1, 'Int8'))
|
||||
```
|
||||
|
||||
SELECT defaultValueOfArgumentType(CAST(1, 'Int8'))
|
||||
```response
|
||||
┌─defaultValueOfArgumentType(CAST(1, 'Int8'))─┐
|
||||
│ 0 │
|
||||
└─────────────────────────────────────────────┘
|
||||
```
|
||||
|
||||
┌─defaultValueOfArgumentType(CAST(1, 'Int8'))─┐
|
||||
│ 0 │
|
||||
└─────────────────────────────────────────────┘
|
||||
|
||||
1 rows in set. Elapsed: 0.002 sec.
|
||||
|
||||
:) SELECT defaultValueOfArgumentType( CAST(1 AS Nullable(Int8) ) )
|
||||
|
||||
SELECT defaultValueOfArgumentType(CAST(1, 'Nullable(Int8)'))
|
||||
|
||||
┌─defaultValueOfArgumentType(CAST(1, 'Nullable(Int8)'))─┐
|
||||
│ ᴺᵁᴸᴸ │
|
||||
└───────────────────────────────────────────────────────┘
|
||||
|
||||
1 rows in set. Elapsed: 0.002 sec.
|
||||
```sql
|
||||
SELECT defaultValueOfArgumentType(CAST(1, 'Nullable(Int8)'))
|
||||
```
|
||||
|
||||
```response
|
||||
┌─defaultValueOfArgumentType(CAST(1, 'Nullable(Int8)'))─┐
|
||||
│ ᴺᵁᴸᴸ │
|
||||
└───────────────────────────────────────────────────────┘
|
||||
```
|
||||
|
||||
## indexHint {#indexhint}
|
||||
输出符合索引选择范围内的所有数据，同时不实用参数中的表达式进行过滤。
|
||||
@ -496,7 +497,8 @@ FROM
|
||||
|
||||
```
|
||||
SELECT count() FROM ontime
|
||||
|
||||
```
|
||||
```response
|
||||
┌─count()─┐
|
||||
│ 4276457 │
|
||||
└─────────┘
|
||||
@ -506,9 +508,11 @@ SELECT count() FROM ontime
|
||||
|
||||
对该表进行如下的查询：
|
||||
|
||||
```sql
|
||||
SELECT FlightDate AS k, count() FROM ontime GROUP BY k ORDER BY k
|
||||
```
|
||||
:) SELECT FlightDate AS k, count() FROM ontime GROUP BY k ORDER BY k
|
||||
|
||||
```response
|
||||
SELECT
|
||||
FlightDate AS k,
|
||||
count()
|
||||
@ -530,9 +534,11 @@ ORDER BY k ASC
|
||||
|
||||
在这个查询中，由于没有使用索引，所以ClickHouse将处理整个表的所有数据(`Processed 4.28 million rows`)。使用下面的查询尝试使用索引进行查询：
|
||||
|
||||
```sql
|
||||
SELECT FlightDate AS k, count() FROM ontime WHERE k = '2017-09-15' GROUP BY k ORDER BY k
|
||||
```
|
||||
:) SELECT FlightDate AS k, count() FROM ontime WHERE k = '2017-09-15' GROUP BY k ORDER BY k
|
||||
|
||||
```response
|
||||
SELECT
|
||||
FlightDate AS k,
|
||||
count()
|
||||
@ -552,9 +558,11 @@ ORDER BY k ASC
|
||||
|
||||
现在将表达式`k = '2017-09-15'`传递给`indexHint`函数：
|
||||
|
||||
```sql
|
||||
SELECT FlightDate AS k, count() FROM ontime WHERE indexHint(k = '2017-09-15') GROUP BY k ORDER BY k
|
||||
```
|
||||
:) SELECT FlightDate AS k, count() FROM ontime WHERE indexHint(k = '2017-09-15') GROUP BY k ORDER BY k
|
||||
|
||||
```response
|
||||
SELECT
|
||||
FlightDate AS k,
|
||||
count()
|
||||
|
||||
@ -21,13 +21,13 @@ UUID类型的值。
|
||||
|
||||
此示例演示如何在表中创建UUID类型的列，并对其写入数据。
|
||||
|
||||
``` sql
|
||||
:) CREATE TABLE t_uuid (x UUID) ENGINE=TinyLog
|
||||
|
||||
:) INSERT INTO t_uuid SELECT generateUUIDv4()
|
||||
|
||||
:) SELECT * FROM t_uuid
|
||||
```sql
|
||||
CREATE TABLE t_uuid (x UUID) ENGINE=TinyLog
|
||||
INSERT INTO t_uuid SELECT generateUUIDv4()
|
||||
SELECT * FROM t_uuid
|
||||
```
|
||||
|
||||
```response
|
||||
┌────────────────────────────────────x─┐
|
||||
│ f4bf890f-f9dc-4332-ad5c-0c18e73f28e9 │
|
||||
└──────────────────────────────────────┘
|
||||
@ -47,9 +47,11 @@ UUID类型的值
|
||||
|
||||
**使用示例**
|
||||
|
||||
``` sql
|
||||
:) SELECT toUUID('61f0c404-5cb3-11e7-907b-a6006ad3dba0') AS uuid
|
||||
```sql
|
||||
SELECT toUUID('61f0c404-5cb3-11e7-907b-a6006ad3dba0') AS uuid
|
||||
```
|
||||
|
||||
```response
|
||||
┌─────────────────────────────────uuid─┐
|
||||
│ 61f0c404-5cb3-11e7-907b-a6006ad3dba0 │
|
||||
└──────────────────────────────────────┘
|
||||
@ -70,10 +72,12 @@ UUIDStringToNum(String)
|
||||
**使用示例**
|
||||
|
||||
``` sql
|
||||
:) SELECT
|
||||
SELECT
|
||||
'612f3c40-5d3b-217e-707b-6a546a3d7b29' AS uuid,
|
||||
UUIDStringToNum(uuid) AS bytes
|
||||
```
|
||||
|
||||
```response
|
||||
┌─uuid─────────────────────────────────┬─bytes────────────┐
|
||||
│ 612f3c40-5d3b-217e-707b-6a546a3d7b29 │ a/<@];!~p{jTj={) │
|
||||
└──────────────────────────────────────┴──────────────────┘
|
||||
@ -97,7 +101,8 @@ UUIDNumToString(FixedString(16))
|
||||
SELECT
|
||||
'a/<@];!~p{jTj={)' AS bytes,
|
||||
UUIDNumToString(toFixedString(bytes, 16)) AS uuid
|
||||
|
||||
```
|
||||
```response
|
||||
┌─bytes────────────┬─uuid─────────────────────────────────┐
|
||||
│ a/<@];!~p{jTj={) │ 612f3c40-5d3b-217e-707b-6a546a3d7b29 │
|
||||
└──────────────────┴──────────────────────────────────────┘
|
||||
|
||||
@ -143,7 +143,7 @@ SELECT
|
||||
FROM test.Orders;
|
||||
```
|
||||
|
||||
``` text
|
||||
``` response
|
||||
┌─OrderYear─┬─OrderMonth─┬─OrderDay─┬─OrderHour─┬─OrderMinute─┬─OrderSecond─┐
|
||||
│ 2008 │ 10 │ 11 │ 13 │ 23 │ 44 │
|
||||
└───────────┴────────────┴──────────┴───────────┴─────────────┴─────────────┘
|
||||
@ -161,7 +161,7 @@ FROM test.Orders;
|
||||
SELECT now() AS current_date_time, current_date_time + INTERVAL 4 DAY + INTERVAL 3 HOUR
|
||||
```
|
||||
|
||||
``` text
|
||||
``` response
|
||||
┌───current_date_time─┬─plus(plus(now(), toIntervalDay(4)), toIntervalHour(3))─┐
|
||||
│ 2019-10-23 11:16:28 │ 2019-10-27 14:16:28 │
|
||||
└─────────────────────┴────────────────────────────────────────────────────────┘
|
||||
@ -226,18 +226,14 @@ ClickHouse 支持 `IS NULL` 和 `IS NOT NULL` 。
|
||||
|
||||
<!-- -->
|
||||
|
||||
``` bash
|
||||
:) SELECT x+100 FROM t_null WHERE y IS NULL
|
||||
|
||||
SELECT x + 100
|
||||
FROM t_null
|
||||
WHERE isNull(y)
|
||||
``` sql
|
||||
SELECT x+100 FROM t_null WHERE y IS NULL
|
||||
```
|
||||
|
||||
``` response
|
||||
┌─plus(x, 100)─┐
|
||||
│ 101 │
|
||||
└──────────────┘
|
||||
|
||||
1 rows in set. Elapsed: 0.002 sec.
|
||||
```
|
||||
|
||||
### IS NOT NULL {#is-not-null}
|
||||
@ -249,16 +245,12 @@ WHERE isNull(y)
|
||||
|
||||
<!-- -->
|
||||
|
||||
``` bash
|
||||
:) SELECT * FROM t_null WHERE y IS NOT NULL
|
||||
|
||||
SELECT *
|
||||
FROM t_null
|
||||
WHERE isNotNull(y)
|
||||
``` sql
|
||||
SELECT * FROM t_null WHERE y IS NOT NULL
|
||||
```
|
||||
|
||||
``` response
|
||||
┌─x─┬─y─┐
|
||||
│ 2 │ 3 │
|
||||
└───┴───┘
|
||||
|
||||
1 rows in set. Elapsed: 0.002 sec.
|
||||
```
|
||||
|
||||
@ -27,7 +27,7 @@ A table with data parsed from `data` argument according specified format and ext
|
||||
|
||||
**Query:**
|
||||
``` sql
|
||||
:) select * from format(JSONEachRow,
|
||||
SELECT * FROM format(JSONEachRow,
|
||||
$$
|
||||
{"a": "Hello", "b": 111}
|
||||
{"a": "World", "b": 123}
|
||||
@ -38,7 +38,7 @@ $$)
|
||||
|
||||
**Result:**
|
||||
|
||||
```text
|
||||
```response
|
||||
┌───b─┬─a─────┐
|
||||
│ 111 │ Hello │
|
||||
│ 123 │ World │
|
||||
@ -49,8 +49,7 @@ $$)
|
||||
|
||||
**Query:**
|
||||
```sql
|
||||
|
||||
:) desc format(JSONEachRow,
|
||||
DESC format(JSONEachRow,
|
||||
$$
|
||||
{"a": "Hello", "b": 111}
|
||||
{"a": "World", "b": 123}
|
||||
@ -61,7 +60,7 @@ $$)
|
||||
|
||||
**Result:**
|
||||
|
||||
```text
|
||||
```response
|
||||
┌─name─┬─type──────────────┬─default_type─┬─default_expression─┬─comment─┬─codec_expression─┬─ttl_expression─┐
|
||||
│ b │ Nullable(Float64) │ │ │ │ │ │
|
||||
│ a │ Nullable(String) │ │ │ │ │ │
|
||||
|
||||
Loading…
Reference in New Issue
Block a user