ClickHouse/docs/en/engines/database-engines/mysql.md
2021-07-29 18:20:55 +03:00

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---
toc_priority: 30
toc_title: MySQL
---
# MySQL {#mysql}
Allows to connect to databases on a remote MySQL server and perform `INSERT` and `SELECT` queries to exchange data between ClickHouse and MySQL.
The `MySQL` database engine translate queries to the MySQL server so you can perform operations such as `SHOW TABLES` or `SHOW CREATE TABLE`.
You cannot perform the following queries:
- `RENAME`
- `CREATE TABLE`
- `ALTER`
## Creating a Database {#creating-a-database}
``` sql
CREATE DATABASE [IF NOT EXISTS] db_name [ON CLUSTER cluster]
ENGINE = MySQL('host:port', ['database' | database], 'user', 'password')
```
**Engine Parameters**
- `host:port` — MySQL server address.
- `database` — Remote database name.
- `user` — MySQL user.
- `password` — User password.
## Data Types Support {#data_types-support}
| MySQL | ClickHouse |
|----------------------------------|--------------------------------------------------------------|
| UNSIGNED TINYINT | [UInt8](../../sql-reference/data-types/int-uint.md) |
| TINYINT | [Int8](../../sql-reference/data-types/int-uint.md) |
| UNSIGNED SMALLINT | [UInt16](../../sql-reference/data-types/int-uint.md) |
| SMALLINT | [Int16](../../sql-reference/data-types/int-uint.md) |
| UNSIGNED INT, UNSIGNED MEDIUMINT | [UInt32](../../sql-reference/data-types/int-uint.md) |
| INT, MEDIUMINT | [Int32](../../sql-reference/data-types/int-uint.md) |
| UNSIGNED BIGINT | [UInt64](../../sql-reference/data-types/int-uint.md) |
| BIGINT | [Int64](../../sql-reference/data-types/int-uint.md) |
| FLOAT | [Float32](../../sql-reference/data-types/float.md) |
| DOUBLE | [Float64](../../sql-reference/data-types/float.md) |
| DATE | [Date](../../sql-reference/data-types/date.md) |
| DATETIME, TIMESTAMP | [DateTime](../../sql-reference/data-types/datetime.md) |
| BINARY | [FixedString](../../sql-reference/data-types/fixedstring.md) |
All other MySQL data types are converted into [String](../../sql-reference/data-types/string.md).
[Nullable](../../sql-reference/data-types/nullable.md) is supported.
## Global Variables Support {#global-variables-support}
For better compatibility you may address global variables in MySQL style, as `@@identifier`.
These variables are supported:
- `version`
- `max_allowed_packet`
!!! warning "Warning"
By now these variables are stubs and don't correspond to anything.
Example:
``` sql
SELECT @@version;
```
## Examples of Use {#examples-of-use}
Table in MySQL:
``` text
mysql> USE test;
Database changed
mysql> CREATE TABLE `mysql_table` (
-> `int_id` INT NOT NULL AUTO_INCREMENT,
-> `float` FLOAT NOT NULL,
-> PRIMARY KEY (`int_id`));
Query OK, 0 rows affected (0,09 sec)
mysql> insert into mysql_table (`int_id`, `float`) VALUES (1,2);
Query OK, 1 row affected (0,00 sec)
mysql> select * from mysql_table;
+------+-----+
| int_id | value |
+------+-----+
| 1 | 2 |
+------+-----+
1 row in set (0,00 sec)
```
Database in ClickHouse, exchanging data with the MySQL server:
``` sql
CREATE DATABASE mysql_db ENGINE = MySQL('localhost:3306', 'test', 'my_user', 'user_password')
```
``` sql
SHOW DATABASES
```
``` text
┌─name─────┐
│ default │
│ mysql_db │
│ system │
└──────────┘
```
``` sql
SHOW TABLES FROM mysql_db
```
``` text
┌─name─────────┐
│ mysql_table │
└──────────────┘
```
``` sql
SELECT * FROM mysql_db.mysql_table
```
``` text
┌─int_id─┬─value─┐
│ 1 │ 2 │
└────────┴───────┘
```
``` sql
INSERT INTO mysql_db.mysql_table VALUES (3,4)
```
``` sql
SELECT * FROM mysql_db.mysql_table
```
``` text
┌─int_id─┬─value─┐
│ 1 │ 2 │
│ 3 │ 4 │
└────────┴───────┘
```
[Original article](https://clickhouse.tech/docs/en/database_engines/mysql/) <!--hide-->