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Add named collections to mysql table function docs

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Aliaksei Khatskevich 2023-12-06 22:33:03 +01:00
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26
docs/en/sql-reference/table-functions/mysql.md
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@ -11,31 +11,25 @@ Allows `SELECT` and `INSERT` queries to be performed on data that is stored on a
**Syntax** **Syntax**
``` sql ``` sql
mysql('host:port', 'database', 'table', 'user', 'password'[, replace_query, 'on_duplicate_clause']) mysql({host:port, database, table, user, password[, replace_query, on_duplicate_clause] | named_collection[, option=value [,..]]})
``` ```
**Arguments** **Parameters**
- `host:port` — MySQL server address. - `host:port` — MySQL server address.
- `database` — Remote database name. - `database` — Remote database name.
- `table` — Remote table name. - `table` — Remote table name.
- `user` — MySQL user. - `user` — MySQL user.
- `password` — User password. - `password` — User password.
- `replace_query` — Flag that converts `INSERT INTO` queries to `REPLACE INTO`. Possible values: - `replace_query` — Flag that converts `INSERT INTO` queries to `REPLACE INTO`. Possible values:
- `0` - The query is executed as `INSERT INTO`. - `0` - The query is executed as `INSERT INTO`.
- `1` - The query is executed as `REPLACE INTO`. - `1` - The query is executed as `REPLACE INTO`.
- `on_duplicate_clause` — The `ON DUPLICATE KEY on_duplicate_clause` expression that is added to the `INSERT` query. Can be specified only with `replace_query = 0` (if you simultaneously pass `replace_query = 1` and `on_duplicate_clause`, ClickHouse generates an exception). - `on_duplicate_clause` — The `ON DUPLICATE KEY on_duplicate_clause` expression that is added to the `INSERT` query. Can be specified only with `replace_query = 0` (if you simultaneously pass `replace_query = 1` and `on_duplicate_clause`, ClickHouse generates an exception).
Example: `INSERT INTO t (c1,c2) VALUES ('a', 2) ON DUPLICATE KEY UPDATE c2 = c2 + 1;` Example: `INSERT INTO t (c1,c2) VALUES ('a', 2) ON DUPLICATE KEY UPDATE c2 = c2 + 1;`
`on_duplicate_clause` here is `UPDATE c2 = c2 + 1`. See the MySQL documentation to find which `on_duplicate_clause` you can use with the `ON DUPLICATE KEY` clause. `on_duplicate_clause` here is `UPDATE c2 = c2 + 1`. See the MySQL documentation to find which `on_duplicate_clause` you can use with the `ON DUPLICATE KEY` clause.
Arguments also can be passed using [named collections](/docs/en/operations/named-collections.md). In this case `host` and `port` should be specified separately. This approach is recommended for production environment.
Simple `WHERE` clauses such as `=, !=, >, >=, <, <=` are currently executed on the MySQL server. Simple `WHERE` clauses such as `=, !=, >, >=, <, <=` are currently executed on the MySQL server.
The rest of the conditions and the `LIMIT` sampling constraint are executed in ClickHouse only after the query to MySQL finishes. The rest of the conditions and the `LIMIT` sampling constraint are executed in ClickHouse only after the query to MySQL finishes.
@ -86,6 +80,18 @@ Selecting data from ClickHouse:
SELECT * FROM mysql('localhost:3306', 'test', 'test', 'bayonet', '123'); SELECT * FROM mysql('localhost:3306', 'test', 'test', 'bayonet', '123');
``` ```
Or using [named collections](/docs/en/operations/named-collections.md):
```sql
CREATE NAMED COLLECTION creds AS
host = 'localhost',
port = 3306,
database = 'test',
user = 'bayonet',
password = '123';
SELECT * FROM mysql(creds, table='test');
```
``` text ``` text
┌─int_id─┬─float─┐ ┌─int_id─┬─float─┐
│ 1 │ 2 │ │ 1 │ 2 │