DELETE |V2.2.77|OceanBase Database| docs|Distributed Database

DELETE

Last Updated：2023-08-18 09:26:34 Updated

Description

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

Syntax

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

Multiple-Table-Delete Syntax:
    DELETE [hint_options] tbl_name[.*] [, tbl_name[.*]] ...
    FROM table_references
    [WHERE where_condition]
Or:
    DELETE [hint_options] FROM tbl_name[.*] [, tbl_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:
    {tbl_name | joined_table | table_subquery | select_with_parens} [, ...]

Parameters

Parameter	Description
hint_options	The hint options.
tbl_name	The name of the table to be deleted.
partition_name	The name of the partition in the table to be deleted.
where_condition	The filtering condition that must be met for a table to be deleted.
order_expression_list	The list of sort keys for the table to be deleted.
row_count	The number of rows to be deleted from the table. The specified value must be an integer.
table_references	The sequence of tables to be selected when you delete data in two or more tables.

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 from Table t1. Column c1 is the primary key column of Table t1.

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 Column c2 from Table t1.

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 Partition p2 from Table t2.

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 two 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 two 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, 4 rows affected (0.02 sec)

obclient> select * from t1;
+----+------+
| c1 | c2   |
+----+------+
|  4 |    4 |
+----+------+
1 row in set (0.01 sec)

obclient> select * from t2;
Empty set (0.01 sec)

Delete data in two 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)

Delete 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)

Note

Subqueries cannot be directly deleted regardless of whether you delete data from one or more tables. For example:

delete from (select * from t1);