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如何在MySQL中的select中使用if / else条件？

2024-04-29 00:05:03 368

让我们首先创建一个表-

mysql> create table DemoTable1966
   (
   UserId int NOT NULL AUTO_INCREMENT PRIMARY KEY,
   UserName varchar(20),
   PhotoLiked int
   );

使用插入命令在表中插入一些记录-

mysql> insert into DemoTable1966(UserName,PhotoLiked) values('Chris',57);
mysql> insert into DemoTable1966(UserName,PhotoLiked) values('David',100);
mysql> insert into DemoTable1966(UserName,PhotoLiked) values('Mike',68);
mysql> insert into DemoTable1966(UserName,PhotoLiked) values('Sam',78);

使用select语句显示表中的所有记录-

mysql> select * from DemoTable1966;

这将产生以下输出-

+--------+----------+------------+
| UserId | UserName | PhotoLiked |
+--------+----------+------------+
|      1 | Chris    |         57 |
|      2 | David    |        100 |
|      3 | Mike     |         68 |
|      4 | Sam      |         78 |
+--------+----------+------------+
4 rows in set (0.00 sec)

这是在MySQLSELECT中使用if/else条件的查询-

mysql> select if(PhotoLiked > 75,UserName,'Likes are less') as Result from DemoTable1966;

这将产生以下输出-

+------------------------------------------------+
| Result                                         |
+------------------------------------------------+
| Likes are less                                 |
| David                                          |
| Likes are less                                 |
| Sam                                            |
+------------------------------------------------+
4 rows in set (0.00 sec)

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如何在MySQL中的select中使用if / else条件？

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