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

machine_translated	machine_translated_rev	toc_priority	toc_title
true	72537a2d52	42	mysql

mysql

允许 SELECT 要对存储在远程MySQL服务器上的数据执行的查询。

mysql('host:port', 'database', 'table', 'user', 'password'[, replace_query, 'on_duplicate_clause']);

参数

• host:port — MySQL server address.

• database — Remote database name.

• table — Remote table name.

• user — MySQL user.

• password — User password.

• replace_query — Flag that converts INSERT INTO 查询到 REPLACE INTO. 如果 replace_query=1，查询被替换。

• on_duplicate_clause — The ON DUPLICATE KEY on_duplicate_clause 表达式被添加到 INSERT 查询。

  Example: `INSERT INTO t (c1,c2) VALUES ('a', 2) ON DUPLICATE KEY UPDATE c2 = c2 + 1`, where `on_duplicate_clause` is `UPDATE c2 = c2 + 1`. See the MySQL documentation to find which `on_duplicate_clause` you can use with the `ON DUPLICATE KEY` clause.
  
  To specify `on_duplicate_clause` you need to pass `0` to the `replace_query` parameter. If you simultaneously pass `replace_query = 1` and `on_duplicate_clause`, ClickHouse generates an exception.
  

简单 WHERE 条款如 =, !=, >, >=, <, <= 当前在MySQL服务器上执行。

其余的条件和 LIMIT 只有在对MySQL的查询完成后，才会在ClickHouse中执行采样约束。

返回值

与原始MySQL表具有相同列的table对象。

用法示例

MySQL中的表:

mysql> CREATE TABLE `test`.`test` (
    ->   `int_id` INT NOT NULL AUTO_INCREMENT,
    ->   `int_nullable` INT NULL DEFAULT NULL,
    ->   `float` FLOAT NOT NULL,
    ->   `float_nullable` FLOAT NULL DEFAULT NULL,
    ->   PRIMARY KEY (`int_id`));
Query OK, 0 rows affected (0,09 sec)

mysql> insert into test (`int_id`, `float`) VALUES (1,2);
Query OK, 1 row affected (0,00 sec)

mysql> select * from test;
+------+----------+-----+----------+
| int_id | int_nullable | float | float_nullable |
+------+----------+-----+----------+
|      1 |         NULL |     2 |           NULL |
+------+----------+-----+----------+
1 row in set (0,00 sec)

从ClickHouse中选择数据:

SELECT * FROM mysql('localhost:3306', 'test', 'test', 'bayonet', '123')

┌─int_id─┬─int_nullable─┬─float─┬─float_nullable─┐
│      1 │         ᴺᵁᴸᴸ │     2 │           ᴺᵁᴸᴸ │
└────────┴──────────────┴───────┴────────────────┘

另请参阅

• 该 ‘MySQL’ 表引擎
• 使用MySQL作为外部字典的来源

原始文章