ClickHouse/docs/zh/engines/database-engines/mysql.md
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# 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`
## CREATE DATABASE {#create-database}
``` sql
CREATE DATABASE [IF NOT EXISTS] db_name [ON CLUSTER cluster]
ENGINE = MySQL('host:port', ['database' | database], 'user', 'password')
```
**MySQL数据库引擎参数**
- `host:port` — 链接的MySQL地址。
- `database` — 链接的MySQL数据库。
- `user` — 链接的MySQL用户。
- `password` — 链接的MySQL用户密码。
## 支持的类型对应 {#zhi-chi-de-lei-xing-dui-ying}
| 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 | [日期](../../sql-reference/data-types/date.md) |
| DATETIME, TIMESTAMP | [日期时间](../../sql-reference/data-types/datetime.md) |
| BINARY | [固定字符串](../../sql-reference/data-types/fixedstring.md) |
其他的MySQL数据类型将全部都转换为[字符串](../../sql-reference/data-types/string.md)。
同时以上的所有类型都支持[可为空](../../sql-reference/data-types/nullable.md)。
## 使用示例 {#shi-yong-shi-li}
在MySQL中创建表:
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)
在ClickHouse中创建MySQL类型的数据库同时与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.tech/docs/en/database_engines/mysql/) <!--hide-->