WHERE约束 where字句中可以使用：比较运算符：>< >= <= != between 80 and 100 值在80到100之间 >=80 <=100 in(80,90,100) 值是80或90或100 满足这个条件就可以 like egon%pattern可以是%或_，%表示任意多字符_表示一个字符 逻辑运算符：在多个条件直接可以使用逻辑运算符 and or not select id,name,age from employee where id >7; 执行顺序 1.from employee 2. where id >7 3. id,name,age 先找到表 再按照约束条件...
需求找出年龄是 81 或者 73 或者 28 mysql> select * from employee where age=81 or age=73 or age=28; +----+-----------+--------+-----+------------+-----------+--------------+----------+--------+-----------+ | id | name | sex | age | hire_date | post | post_comment | salary | office | depart_id | +----+-----------+--------+-----+------------+-----------+--------------+----------+----...