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

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---
2022-08-26 19:07:59 +00:00
slug: /zh/engines/database-engines/mysql
2022-04-10 23:08:18 +00:00
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]
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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-->