将IF语句插入MySQL查询的正确方法是什么？
要将IF语句插入MySQL查询，请使用以下语法：
select yourColumnName ,if(yourCondition, yourStatement1,yourStatement2) from yourTableName;
让我们首先创建一个表-
mysql> create table DemoTable1571 -> ( -> Id int, -> Value int -> );
使用插入命令在表中插入一些记录-
mysql> insert into DemoTable1571 values(101,500); mysql> insert into DemoTable1571 values(102,450); mysql> insert into DemoTable1571 values(103,300); mysql> insert into DemoTable1571 values(104,700);
使用select语句显示表中的所有记录-
mysql> select * from DemoTable1571;
这将产生以下输出
+------+-------+ | Id | Value | +------+-------+ | 101 | 500 | | 102 | 450 | | 103 | 300 | | 104 | 700 | +------+-------+ 4 rows in set (0.00 sec)
这是将if语句正确插入MySQL查询的查询。
mysql> select Value,if(Value > 550, 'Value is greater than 550','Value is less than 550') from DemoTable1571;
这将产生以下输出-
+-------+-----------------------------------------------------------------------+ | Value | if(Value > 550, 'Value is greater than 550','Value is less than 550') | +-------+-----------------------------------------------------------------------+ | 500 | Value is less than 550 | | 450 | Value is less than 550 | | 300 | Value is less than 550 | | 700 | Value is greater than 550 | +-------+-----------------------------------------------------------------------+ 4 rows in set (0.00 sec)