DELETE

Purpose

You can use this statement to delete rows that meet the conditions from one or more tables.

Direct DELETE operations on subqueries are not supported for either a single table or multiple tables. For example, the following statement cannot be executed: DELETE FROM (SELECT * FROM t1);.

Syntax

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} [, ...]
 

Parameters

Examples

Execute the following statement to create Table t1 and Table 2 and insert data into them:

obclient> CREATE TABLE t1(c1 INT PRIMARY KEY, c2 INT);
Query OK, 0 rows affected (0.16 sec)
obclient> SELECT * FROM t1;
+----+------+
 c1  c2   
+----+------+
  1     1 
  2     2 
  3     3 
  4     4 
+----+------+
4 rows in set (0.06 sec)

obclient> CREATE TABLE t2(c1 INT PRIMARY KEY, c2 INT) PARTITION BY KEY(c1) PARTITIONS 4;
Query OK, 0 rows affected (0.19 sec)
obclient> SELECT * FROM t2;
+----+------+
 c1  c2   
+----+------+
  5     5 
  1     1 
  2     2 
  3     3 
+----+------+
4 rows in set (0.02 sec)

• Delete data in a single table: Delete rows where c1 = 2. The c1 column is the primary key column of the t1 table.

  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 (0.01 sec)
  

• Delete data in a single table: Delete the data in the first row sorted by the c2 column from the t1 table.

  obclient> DELETE FROM t1 ORDER BY c2 LIMIT 1;
  Query OK, 1 row affected (0.01 sec)
  
  obclient> SELECT * FROM t1;
  +----+------+
   c1  c2   
  +----+------+
    2     2 
    3     3 
    4     4 
  +----+------+
  3 rows in set (0.00 sec)
  

• Delete data in a single table: Delete data in the p2 partition from the t2 table.

  obclient> DELETE FROM t2 PARTITION(p2);
  Query OK, 3 rows affected (0.02 sec)
  
  obclient> SELECT * FROM t2;
  +----+------+
   c1  c2   
  +----+------+
    5     5 
  +----+------+
  1 row in set (0.02 sec)
  

• Delete data in multiple tables: Delete rows where t1.c1 = t2.c1 from tables t1 and t2.

  obclient> DELETE t1, t2 FROM t1, t2 WHERE t1.c1 = t2.c1;
  Query OK, 3 rows affected (0.02 sec)
  
  obclient> SELECT * FROM t1;
  +----+------+
   c1  c2   
  +----+------+
    4     4 
  +----+------+
  1 row in set (0.01 sec)
  
  obclient> SELECT * FROM t2;
  +----+------+
   c1  c2   
  +----+------+
    5     5 
  +----+------+
  1 row in set (0.01 sec)
  

• Delete data in multiple tables: Delete rows where t1.c1 = t2.c1 from tables t1 and t2.

  obclient> DELETE FROM t1, t2 USING t1,t2 WHERE t1.c1 = t2.c1;
  Query OK, 6 rows affected (0.02 sec)
  
  obclient> SELECT * FROM t1;
  +----+------+
   c1  c2   
  +----+------+
    4     4 
  +----+------+
  1 row in set (0.01 sec)
  
  obclient> SELECT * FROM t2;
  +----+------+
   c1  c2   
  +----+------+
    5     5 
  +----+------+
  1 row in set (0.00 sec)
  

• Delete data in multiple tables: Delete data from partition p2 of table t2 and rows where t1.c1 = t2.c1 from table t1.

  obclient> DELETE t2 FROM t1,t2 PARTITION(p2) WHERE t1.c1 = t2.c1;
  Query OK, 3 rows affected (0.02 sec)
  
  obclient> select * from t2;
  +----+------+
   c1  c2   
  +----+------+
    5     5 
  +----+------+
  1 row in set (0.01 sec)
  

• Drop an updatable view v.

  obclient> CREATE VIEW v AS SELECT * FROM t1;
  Query OK, 0 rows affected (0.07 sec)
  
  obclient> DELETE FROM v WHERE v.c1 = 1;
  Query OK, 1 row affected (0.02 sec)
  
  obclient> SELECT * FROM v;
  +----+------+
   c1  c2   
  +----+------+
    2     2 
    3     3 
    4     4 
  +----+------+
  3 rows in set (0.01 sec)