Mysql中的if语句

1.语法

​​if(expr,a,b)​​：如果expr为真，则取a，否则取b

2.实例

mysql> select if(2>1,3,4);
+-------------+
| if(2>1,3,4) |
+-------------+
|           3 |
+-------------+
1 row in set (0.00 sec)

mysql> select if(2<1,3,4);
+-------------+
| if(2<1,3,4) |
+-------------+
|           4 |
+-------------+
1 row in set (0.00 sec)