DELETE

描述

该语句用来删除表中符合条件的行，包括单表删除及多表删除两种方式。

无论是多表删除还是单表删除都不支持直接对子查询进行删除操作，例如 DELETE FROM (SELECT * FROM t1);。

语法

Single-Table-Delete Syntax:
    DELETE [hint_options] FROM table_name
    [PARTITION (partition_name,...)]
    [WHERE where_condition]
    [ORDER BY order_expression_list]
    [LIMIT row_count]

Multiple-Table-Delete Syntax:
    DELETE [hint_options] table_name[.*] [, table_name[.*]] ...
    FROM table_references
    [WHERE where_condition]
Or:
    DELETE [hint_options] FROM table_name[.*] [, table_name[.*]] ...
    USING table_references
    [WHERE where_condition]
 
where_condition:
    expression

order_expression_list:
    order_expression [, order_expression ...]

order_expression:
    expression [ASC | DESC]

limit_row_count:
    INT_VALUE
  
table_references:
    {table_name | joined_table | table_subquery | select_with_parents} [, ...]
 

参数解释

示例

示例表及数据基于以下定义：

obclient> CREATE TABLE t1(c1 INT PRIMARY KEY, c2 INT);
Query OK, 0 rows affected 
obclient> SELECT * FROM t1;
+----+------+
| c1 | c2   |
+----+------+
|  1 |    1 |
|  2 |    2 |
|  3 |    3 |
|  4 |    4 |
+----+------+
4 rows in set 

obclient> CREATE TABLE t2(c1 INT PRIMARY KEY, c2 INT) PARTITION BY KEY(c1) PARTITIONS 4;
Query OK, 0 rows affected 
obclient> SELECT * FROM t2;
+----+------+
| c1 | c2   |
+----+------+
|  5 |    5 |
|  1 |    1 |
|  2 |    2 |
|  3 |    3 |
+----+------+
4 rows in set 

• 单表删除：删除 c1=2 的行，其中 c1 列为表 t1 中的 Primary Key。

  obclient> DELETE FROM t1 WHERE c1 = 2;
  Query OK, 1 row affected (0.02 sec)
  
  obclient> SELECT * FROM t1;
  +----+------+
  | c1 | c2   |
  +----+------+
  |  1 |    1 |
  |  3 |    3 |
  |  4 |    4 |
  +----+------+
  3 rows in set 
  

• 单表删除：删除表 t1 的按照 c2 列排序之后的第一行数据。

  obclient> DELETE FROM t1 ORDER BY c2 LIMIT 1;
  Query OK, 1 row affected 
  
  obclient> SELECT * FROM t1;
  +----+------+
  | c1 | c2   |
  +----+------+
  |  2 |    2 |
  |  3 |    3 |
  |  4 |    4 |
  +----+------+
  3 rows in set 
  

• 单表删除：执行删除表 t2 的 p2 分区的数据。

  obclient> DELETE FROM t2 PARTITION(p2);
  Query OK, 3 rows affected 
  
  obclient> SELECT * FROM t2;
  +----+------+
  | c1 | c2   |
  +----+------+
  |  5 |    5 |
  +----+------+
  1 row in set 
  

• 多表删除：删除 t1，t2 表中 t1.c1 = t2.c1 的数据。

  obclient> DELETE t1, t2 FROM t1, t2 WHERE t1.c1 = t2.c1;
  Query OK, 3 rows affected 
  
  obclient> SELECT * FROM t1;
  +----+------+
  | c1 | c2   |
  +----+------+
  |  4 |    4 |
  +----+------+
  1 row in set 
  
  obclient> SELECT * FROM t2;
  +----+------+
  | c1 | c2   |
  +----+------+
  |  5 |    5 |
  +----+------+
  1 row in set 
  

• 多表删除：删除 t1，t2 表中 t1.c1 = t2.c1 的数据。

  obclient> DELETE FROM t1, t2 USING t1,t2 WHERE t1.c1 = t2.c1;
  Query OK, 6 rows affected 
  
  obclient> SELECT * FROM t1;
  +----+------+
  | c1 | c2   |
  +----+------+
  |  4 |    4 |
  +----+------+
  1 row in set 
  
  obclient> SELECT * FROM t2;
  +----+------+
  | c1 | c2   |
  +----+------+
  |  5 |    5 |
  +----+------+
  1 row in set 
  

• 多表删除：删除 t2 表中的 p2 分区中和 t1 表中满足 t1.c1 = t2.c1 的数据。

  obclient> DELETE t2 FROM t1,t2 PARTITION(p2) WHERE t1.c1 = t2.c1;
  Query OK, 3 rows affected 
  
  obclient> select * from t2;
  +----+------+
  | c1 | c2   |
  +----+------+
  |  5 |    5 |
  +----+------+
  1 row in set
  

• 对可更新视图 v 进行删除操作。

  obclient> CREATE VIEW v AS SELECT * FROM t1;
  Query OK, 0 rows affected 
  
  obclient> DELETE FROM v WHERE v.c1 = 1;
  Query OK, 1 row affected 
  
  obclient> SELECT * FROM v;
  +----+------+
  | c1 | c2   |
  +----+------+
  |  2 |    2 |
  |  3 |    3 |
  |  4 |    4 |
  +----+------+
  3 rows in set