ClickHouse/docs/en/sql-reference/table-functions/mysql.md

114 lines
3.5 KiB
Markdown
Raw Normal View History

2020-04-03 13:23:32 +00:00
---
toc_priority: 42
toc_title: mysql
---
2020-03-20 10:10:48 +00:00
# mysql {#mysql}
2020-12-28 23:43:47 +00:00
Allows `SELECT` and `INSERT` queries to be performed on data that is stored on a remote MySQL server.
**Syntax**
2020-03-20 10:10:48 +00:00
``` sql
2020-12-28 23:43:47 +00:00
mysql('host:port', 'database', 'table', 'user', 'password'[, replace_query, 'on_duplicate_clause'])
```
2021-02-15 21:38:32 +00:00
**Arguments**
- `host:port` — MySQL server address.
2020-03-20 10:10:48 +00:00
- `database` — Remote database name.
2020-03-20 10:10:48 +00:00
- `table` — Remote table name.
2020-03-20 10:10:48 +00:00
- `user` — MySQL user.
2020-03-20 10:10:48 +00:00
- `password` — User password.
2020-03-20 10:10:48 +00:00
2020-12-29 22:25:09 +00:00
- `replace_query` — Flag that converts `INSERT INTO` queries to `REPLACE INTO`. Possible values:
- `0` - The query is executed as `INSERT INTO`.
- `1` - The query is executed as `REPLACE INTO`.
2020-03-20 10:10:48 +00:00
2020-12-29 22:25:09 +00:00
- `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).
2020-12-30 06:53:32 +00:00
Example: `INSERT INTO t (c1,c2) VALUES ('a', 2) ON DUPLICATE KEY UPDATE c2 = c2 + 1;`
2020-12-29 22:25:09 +00:00
`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.
2020-03-20 10:10:48 +00:00
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.
Supports multiple replicas that must be listed by `|`. For example:
```sql
2021-06-27 20:26:10 +00:00
SELECT name FROM mysql(`mysql{1|2|3}:3306`, 'mysql_database', 'mysql_table', 'user', 'password');
```
or
```sql
2021-06-27 20:26:10 +00:00
SELECT name FROM mysql(`mysql1:3306|mysql2:3306|mysql3:3306`, 'mysql_database', 'mysql_table', 'user', 'password');
```
**Returned Value**
A table object with the same columns as the original MySQL table.
2020-12-30 21:49:52 +00:00
!!! info "Note"
2021-07-29 15:20:55 +00:00
In the `INSERT` query to distinguish table function `mysql(...)` from table name with column names list, you must use keywords `FUNCTION` or `TABLE FUNCTION`. See examples below.
2020-12-30 21:49:52 +00:00
2020-12-28 23:43:47 +00:00
**Examples**
Table in MySQL:
2020-03-20 10:10:48 +00:00
``` text
mysql> CREATE TABLE `test`.`test` (
-> `int_id` INT NOT NULL AUTO_INCREMENT,
-> `float` FLOAT NOT NULL,
-> PRIMARY KEY (`int_id`));
2020-12-29 22:25:09 +00:00
mysql> INSERT INTO test (`int_id`, `float`) VALUES (1,2);
2020-12-29 22:25:09 +00:00
mysql> SELECT * FROM test;
2020-12-30 06:44:59 +00:00
+--------+-------+
| int_id | float |
+--------+-------+
| 1 | 2 |
+--------+-------+
```
Selecting data from ClickHouse:
2020-03-20 10:10:48 +00:00
``` sql
2020-12-29 22:38:30 +00:00
SELECT * FROM mysql('localhost:3306', 'test', 'test', 'bayonet', '123');
```
2020-03-20 10:10:48 +00:00
``` text
2020-12-30 06:44:59 +00:00
┌─int_id─┬─float─┐
│ 1 │ 2 │
└────────┴───────┘
```
2020-12-28 23:43:47 +00:00
Replacing and inserting:
```sql
2020-12-31 09:06:55 +00:00
INSERT INTO FUNCTION mysql('localhost:3306', 'test', 'test', 'bayonet', '123', 1) (int_id, float) VALUES (1, 3);
INSERT INTO TABLE FUNCTION mysql('localhost:3306', 'test', 'test', 'bayonet', '123', 0, 'UPDATE int_id = int_id + 1') (int_id, float) VALUES (1, 4);
2020-12-28 23:43:47 +00:00
SELECT * FROM mysql('localhost:3306', 'test', 'test', 'bayonet', '123');
```
2020-12-30 06:44:59 +00:00
``` text
┌─int_id─┬─float─┐
│ 1 │ 3 │
│ 2 │ 4 │
└────────┴───────┘
2020-12-28 23:43:47 +00:00
```
**See Also**
- [The MySQL table engine](../../engines/table-engines/integrations/mysql.md)
- [Using MySQL as a source of external dictionary](../../sql-reference/dictionaries/external-dictionaries/external-dicts-dict-sources.md#dicts-external_dicts_dict_sources-mysql)
[Original article](https://clickhouse.com/docs/en/sql-reference/table_functions/mysql/) <!--hide-->