📜  SQL-删除查询

📅  最后修改于: 2020-12-29 04:34:34             🧑  作者: Mango


SQL 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,以删除选定的行,否则将删除所有记录。

句法

带WHERE子句的DELETE查询的基本语法如下-

DELETE FROM table_name
WHERE [condition];

您可以使用AND或OR运算符组合N个条件。

考虑具有以下记录的CUSTOMERS表-

+----+----------+-----+-----------+----------+
| ID | NAME     | AGE | ADDRESS   | SALARY   |
+----+----------+-----+-----------+----------+
|  1 | Ramesh   |  32 | Ahmedabad |  2000.00 |
|  2 | Khilan   |  25 | Delhi     |  1500.00 |
|  3 | kaushik  |  23 | Kota      |  2000.00 |
|  4 | Chaitali |  25 | Mumbai    |  6500.00 |
|  5 | Hardik   |  27 | Bhopal    |  8500.00 |
|  6 | Komal    |  22 | MP        |  4500.00 |
|  7 | Muffy    |  24 | Indore    | 10000.00 |
+----+----------+-----+-----------+----------+

以下代码具有一个查询,该查询将删除ID为6的客户。

SQL> DELETE FROM CUSTOMERS
WHERE ID = 6;

现在,CUSTOMERS表将具有以下记录。

+----+----------+-----+-----------+----------+
| ID | NAME     | AGE | ADDRESS   | SALARY   |
+----+----------+-----+-----------+----------+
|  1 | Ramesh   |  32 | Ahmedabad |  2000.00 |
|  2 | Khilan   |  25 | Delhi     |  1500.00 |
|  3 | kaushik  |  23 | Kota      |  2000.00 |
|  4 | Chaitali |  25 | Mumbai    |  6500.00 |
|  5 | Hardik   |  27 | Bhopal    |  8500.00 |
|  7 | Muffy    |  24 | Indore    | 10000.00 |
+----+----------+-----+-----------+----------+

如果要删除CUSTOMERS表中的所有记录,则无需使用WHERE子句,DELETE查询将如下所示-

SQL> DELETE FROM CUSTOMERS;

现在,CUSTOMERS表将没有任何记录。