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Update syntax.md

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Nikolay Degterinsky 2023-04-10 03:26:43 +02:00 committed by GitHub
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docs/en/sql-reference/syntax.md
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@ -14,7 +14,7 @@ The `INSERT` query uses both parsers:
INSERT INTO t VALUES (1, 'Hello, world'), (2, 'abc'), (3, 'def')
```
The `INSERT INTO t VALUES` fragment is parsed by the full parser, and the data `(1, 'Hello, world'), (2, 'abc'), (3, 'def')` is parsed by the fast stream parser. You can also turn on the full parser for the data by using the [input_format_values_interpret_expressions](../operations/settings/settings-formats.md#settings-input_format_values_interpret_expressions) setting. When `input_format_values_interpret_expressions = 1`, ClickHouse first tries to parse values with the fast stream parser. If it fails, ClickHouse tries to use the full parser for the data, treating it like an SQL [expression](#expressions).
The `INSERT INTO t VALUES` fragment is parsed by the full parser, and the data `(1, 'Hello, world'), (2, 'abc'), (3, 'def')` is parsed by the fast stream parser. You can also turn on the full parser for the data by using the [input_format_values_interpret_expressions](../operations/settings/settings-formats.md#input_format_values_interpret_expressions) setting. When `input_format_values_interpret_expressions = 1`, ClickHouse first tries to parse values with the fast stream parser. If it fails, ClickHouse tries to use the full parser for the data, treating it like an SQL [expression](#expressions).
Data can have any format. When a query is received, the server calculates no more than [max_query_size](../operations/settings/settings.md#settings-max_query_size) bytes of the request in RAM (by default, 1 MB), and the rest is stream parsed.
It allows for avoiding issues with large `INSERT` queries.
@ -108,7 +108,7 @@ Depending on the data format (input or output), `NULL` may have a different repr
There are many nuances to processing `NULL`. For example, if at least one of the arguments of a comparison operation is `NULL`, the result of this operation is also `NULL`. The same is true for multiplication, addition, and other operations. For more information, read the documentation for each operation.
In queries, you can check `NULL` using the [IS NULL](../sql-reference/operators/index.md#operator-is-null) and [IS NOT NULL](../sql-reference/operators/index.md) operators and the related functions `isNull` and `isNotNull`.
In queries, you can check `NULL` using the [IS NULL](../sql-reference/operators/index.md#is-null) and [IS NOT NULL](../sql-reference/operators/index.md#is-not-null) operators and the related functions `isNull` and `isNotNull`.
### Heredoc
@ -213,7 +213,7 @@ expr AS alias
For example, `SELECT table_name_alias.column_name FROM table_name table_name_alias`.
In the [CAST](./functions/type-conversion-functions.md#type_conversion_function-cast) function, the `AS` keyword has another meaning. See the description of the function.
In the [CAST](./functions/type-conversion-functions.md#castx-t) function, the `AS` keyword has another meaning. See the description of the function.
- `expr` — Any expression supported by ClickHouse.
@ -254,7 +254,7 @@ Received exception from server (version 18.14.17):
Code: 184. DB::Exception: Received from localhost:9000, 127.0.0.1. DB::Exception: Aggregate function sum(b) is found inside another aggregate function in query.
```
In this example, we declared table `t` with column `b`. Then, when selecting data, we defined the `sum(b) AS b` alias. As aliases are global, ClickHouse substituted the literal `b` in the expression `argMax(a, b)` with the expression `sum(b)`. This substitution caused the exception. You can change this default behavior by setting [prefer_column_name_to_alias](../operations/settings/settings.md#prefer_column_name_to_alias) to `1`.
In this example, we declared table `t` with column `b`. Then, when selecting data, we defined the `sum(b) AS b` alias. As aliases are global, ClickHouse substituted the literal `b` in the expression `argMax(a, b)` with the expression `sum(b)`. This substitution caused the exception. You can change this default behavior by setting [prefer_column_name_to_alias](../operations/settings/settings.md#prefer-column-name-to-alias) to `1`.
## Asterisk