如何在MySQL中对数字字符串使用比较运算符？
要将比较运算符用于数字字符串，请使用substring()方法。让我们首先创建一个表-
mysql> create table DemoTable1881 ( UserId int, UserEducationGap varchar(20) );
使用插入命令在表中插入一些记录-
mysql> insert into DemoTable1881 values(101,'5-9'); mysql> insert into DemoTable1881 values(102,'2-4'); mysql> insert into DemoTable1881 values(103,'4-8'); mysql> insert into DemoTable1881 values(104,'7-12');
使用select语句显示表中的所有记录-
mysql> select * from DemoTable1881;
这将产生以下输出-
+--------+------------------+ | UserId | UserEducationGap | +--------+------------------+ | 101 | 5-9 | | 102 | 2-4 | | 103 | 4-8 | | 104 | 7-12 | +--------+------------------+ 4 rows in set (0.00 sec)
这是在MySQL中对数字字符串使用比较运算符的查询
mysql> select * from DemoTable1881 where cast(substring(UserEducationGap, 1, instr(UserEducationGap, '-')-1) as signed) >= 4;
这将产生以下输出-
+--------+------------------+ | UserId | UserEducationGap | +--------+------------------+ | 101 | 5-9 | | 103 | 4-8 | | 104 | 7-12 | +--------+------------------+ 3 rows in set (0.00 sec)