SQL - 删除操作(Delete)

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，以删除所选的行，否则将删除所有记录。

Delete Query - 语法

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。

Delete Query - 示例

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 | Learnfk    |  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。

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+----+----------+-----+-----------+----------+
| 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 | Learnfk    |  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。

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