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MySQL Select 语句中的 IF() 函数？

2023-06-20 10:02:03 406

该IF()函数根据条件返回一个值。

语法如下：

SELECT IF(yourCondition, yourMessageIfConditionBecomesTrue,yourMessageIfConditionBecomesFalse) from yourTableName;
Let us first create a table:
mysql> create table DemoTable
   (
   Value int
   );

使用插入命令在表中插入记录-

mysql> insert into DemoTable values(1000);
mysql> insert into DemoTable values(2000);
mysql> insert into DemoTable values(500);
mysql> insert into DemoTable values(1100);

使用select语句显示表中的所有记录-

mysql> select *from DemoTable;

这将产生以下输出-

+-------+
| Value |
+-------+
| 1000  |
| 2000  |
| 500   |
| 1100  |
+-------+
4 rows in set (0.00 sec)

这是IF()在MySQL中实现的查询-

mysql> select Value,IF(Value > 1000, CONCAT(Value,' is greater than 1000'),CONCAT(Value,' is lower than 1000')) AS Result from DemoTable;

+-------+---------------------------+
| Value | Result                    |
+-------+---------------------------+
| 1000  | 1000 is lower than 1000   |
| 2000  | 2000 is greater than 1000 |
| 500   | 500 is lower than 1000    |
| 1100  | 1100 is greater than 1000 |
+-------+---------------------------+
4 rows in set (0.00 sec)

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MySQL Select 语句中的 IF() 函数？

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