!= 不等于 select empno,ename,job from scott.emp where job!='manager' ^= 不等于 select empno,ename,job from scott.emp where job^='manager' <>不等于 select empno,ename,job from scott.emp where job<>'manager' <小于 select sal from scott.emp where sal<…
1.一般操作符 (1)!= 不等于 select empno,ename,job from scott.emp where job!='manager' (2)^= 不等于 select empno,ename,job from scott.emp where job^='manager' (3)<>不等于 select empno,ename,job from scott.emp where job<>'manager' (4)<小于 (5)>大于 (6)<=小…
1.union:对两个结果集进行并集操作,不包括重复行,同时进行默认规则的排序: SELECT * FROM emp WHERE sal < UNION SELECT * FROM emp WHERE sal BETWEEN AND order by 2.union All:对两个结果集进行并集操作,包括重复行,不进行排序: SELECT * FROM emp WHERE sal < UNION ALL SELECT * FROM emp WHERE sal BETWEEN AND order…
集合操作符UNION/UNION ALLINTERSECTMINUS Union All不排序,不去重,其余均升序且去重.create table e1 as select * from emp where deptno in (10,20);create table e2 as select * from emp where deptno in (20,30); select * from e1 union select * from e2 order by 8select * from e1…
SQL操作符 算术操作符:+加,-减,*乘,/除 比较操作符: <,>,=,!=,<>,<=,>= 常用的判断,<>和!=相同 between $lower_val$ and $hight_val$ between .. and.. 包括两端 --查询20<=age<=21的学生数据 select * from student where age between 20 and 21 not between $lower_val$ and $hig…