Postgresql 简明教程
PostgreSQL - DELETE Query
PostgreSQL DELETE 查询用于从表中删除现有记录。您可以将 WHERE 子句与 DELETE 查询一起使用以删除已选择的行。否则,所有记录都将被删除。
The PostgreSQL DELETE Query is used to delete the existing records from a table. You can use WHERE clause with DELETE query to delete the selected rows. Otherwise, all the records would be deleted.
Syntax
带 WHERE 子句的 DELETE 查询的基本语法如下 −
The basic syntax of DELETE query with WHERE clause is as follows −
DELETE FROM table_name
WHERE [condition];
可以使用 AND 或 OR 运算符组合 N 个条件。
You can combine N number of conditions using AND or OR operators.
Example
考虑表 COMPANY ,具有如下记录 −
Consider the table COMPANY, having records as follows −
# select * from COMPANY;
id | name | age | address | salary
----+-------+-----+-----------+--------
1 | Paul | 32 | California| 20000
2 | Allen | 25 | Texas | 15000
3 | Teddy | 23 | Norway | 20000
4 | Mark | 25 | Rich-Mond | 65000
5 | David | 27 | Texas | 85000
6 | Kim | 22 | South-Hall| 45000
7 | James | 24 | Houston | 10000
(7 rows)
下面是一个示例,此示例将删除 ID 为 7 的客户 −
The following is an example, which would DELETE a customer whose ID is 7 −
testdb=# DELETE FROM COMPANY WHERE ID = 2;
现在,COMPANY 表将包含以下记录 −
Now, COMPANY table will have the following records −
id | name | age | address | salary
----+-------+-----+-------------+--------
1 | Paul | 32 | California | 20000
3 | Teddy | 23 | Norway | 20000
4 | Mark | 25 | Rich-Mond | 65000
5 | David | 27 | Texas | 85000
6 | Kim | 22 | South-Hall | 45000
7 | James | 24 | Houston | 10000
(6 rows)
如果您想从 COMPANY 表中删除所有记录,不需要在 DELETE 查询中使用 WHERE 子句,如下所示 −
If you want to DELETE all the records from COMPANY table, you do not need to use WHERE clause with DELETE queries, which would be as follows −
testdb=# DELETE FROM COMPANY;
现在,COMPANY 表没有任何记录,因为所有记录都被 DELETE 语句删除。
Now, COMPANY table does not have any record because all the records have been deleted by the DELETE statement.