ClickHouse/docs/zh/engines/database-engines/mysql.md

---
slug: /zh/engines/database-engines/mysql
sidebar_position: 30
sidebar_label: MySQL
---

# MySQL {#mysql}

MySQL引擎用于将远程的MySQL服务器中的表映射到ClickHouse中，并允许您对表进行`INSERT`和`SELECT`查询，以方便您在ClickHouse与MySQL之间进行数据交换

`MySQL`数据库引擎会将对其的查询转换为MySQL语法并发送到MySQL服务器中，因此您可以执行诸如`SHOW TABLES`或`SHOW CREATE TABLE`之类的操作。

但您无法对其执行以下操作：

-   `RENAME`
-   `CREATE TABLE`
-   `ALTER`

## 创建数据库 {#creating-a-database}

``` sql
CREATE DATABASE [IF NOT EXISTS] db_name [ON CLUSTER cluster]
ENGINE = MySQL('host:port', ['database' | database], 'user', 'password')
```

**引擎参数**

-   `host:port` — MySQL服务地址
-   `database` — MySQL数据库名称
-   `user` — MySQL用户名
-   `password` — MySQL用户密码

## 支持的数据类型 {#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) |

其他的MySQL数据类型将全部都转换为[String](../../sql-reference/data-types/string.md).

[Nullable](../../sql-reference/data-types/nullable.md)已经支持

## 全局变量支持 {#global-variables-support}

为了更好地兼容，您可以在SQL样式中设置全局变量，如`@@identifier`.

支持这些变量：
- `version`
- `max_allowed_packet`

!!! warning "警告"
到目前为止，这些变量是存根，并且不对应任何内容。

示例:

``` sql
SELECT @@version;
```

## 使用示例 {#examples-of-use}

MySQL操作:

``` 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)
```

ClickHouse中的数据库，与MySQL服务器交换数据:

``` 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 │
└────────┴───────┘
```

[来源文章](https://clickhouse.com/docs/en/database_engines/mysql/) <!--hide-->