1 where 筛选关键字; select * from emp where job 'CLERK' 从emp表中列出 job大于'CLERK'的项 (由于比较的是字符串,所以加单引号) 2 between and select ename,sal from emp where sal between 800 and 1500 从emp表中找到 sal在800和1500之间的项(包括800 1 where 筛选关键字;select * from emp where job >'CLERK'从emp表中列出 job值大于'CLERK'的项 (由于比较的是字符串,所以加单引号) 2 between and select ename,sal from emp where sal between 800 and 1500从emp表中找到 sal值在800和1500之间的项(包括800和1500) 列出他们的ename 和sal 3 空值select ename,sal from emp where comm is null ;列出非空值select ename,sal from emp where comm is not null ;4 模糊查询查询ename中包含ALL的项select ename from emp where ename like '%ALL%' ;%代表0个或多个字符, 次查询目的为了找到ename 值为 ALL 左边和右边具有0个或多个字符的项查询ename第二个字母为A 的项select ename from emp where ename like '_A%' ;oracle知识库oracle知识库下载下载5 转义字符查找ename中带有 % 的项select ename from emp where ename like '%$%%' escape '$' ;指定'$'为转义字符查找% .
转义字符默认为'/' 使用/ 为转义字符时不用写后面的escape ..
6 排序order by select * from dept order by deptno ; (默认升序) select * from dept order by deptno desc ;(按deptno的降序排序)组合使用:select empno,ename from emp where empno 10 order by empno; (先过滤 再排序) select empno,ename from emp order by empno asc,ename desc; 按(empno升序排序) empno相同时按ename 降序排序