如何在MySQL中的select中使用if / else条件？
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)