#运算符
1,算数运算符(+ - * /)
select 1+1;
select 1-1;
select 1*2;
select 1/3; 0.3333---double 类型
select 3 div 2; 整除
select 3/0; null
2.比较运算符(= != >= <=)
select 1 != 1; 0
# is null /is not null /between ... and .../在某个范围内,
# in/not in 是否在集合内
select * from classroom where cid =3
select * from classroom where description is null
3.逻辑运算符(and or !)与或非
select 1=1 and 1=2;
select 1=1 or 1=2;
select !1 = 1;
4.位运算符(& | ^)与,或,异或
select 3 & 2; #2 按位与
select 3 | 2; #3 按位或
select 3 ^ 2; #1 按位异或
select * from classroom where ...
select 子句作用,字段值
from 子句作用,从哪个表或者冲那个结果集中查询
where 子句作用,条件
MySQL进阶之路五(运算符)
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转载自blog.csdn.net/ZhaiAlan/article/details/92794454
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