在MySQL中设置值为0或1的列的条件
要设置条件，请在MySQL中使用CASEWHEN语句。让我们首先创建一个表-
mysql> create table DemoTable -> ( -> Value1 int, -> Value2 int, -> Value3 int, -> Value4 int -> );
使用插入命令在表中插入一些记录-
mysql> insert into DemoTable values(1,0,1,1); mysql> insert into DemoTable values(1,0,1,0); mysql> insert into DemoTable values(1,1,1,1); mysql> insert into DemoTable values(0,0,0,0);
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-
+--------+--------+--------+--------+ | Value1 | Value2 | Value3 | Value4 | +--------+--------+--------+--------+ | 1 | 0 | 1 | 1 | | 1 | 0 | 1 | 0 | | 1 | 1 | 1 | 1 | | 0 | 0 | 0 | 0 | +--------+--------+--------+--------+ 4 rows in set (0.00 sec)
这是在MySQL中设置值为0或1的列的条件的查询-
mysql> select case when Value1+Value2+Value3+Value4 < 2 then 'NotGood' else 'Good' end as Status from DemoTable;
这将产生以下输出-
+---------+ | Status | +---------+ | Good | | Good | | Good | | NotGood | +---------+ 4 rows in set (0.00 sec)