限制选择语句的返回行
语法:
使用,关键字来限制数据行的返回,在子句跟在从子句的后面。
完成,select *,得到emp where deptno=10;
,,,,EMPNO ENAME ,,,,,工作,,,,,,,MGR hiredate,,,,,,萨尔通讯DEPTNO
- - - - - - - - - - -,- - - - - - - - - - -,- - - - - - -安康;- - - - - - - - - - -,- - - - - - - - - - - - - - - - - -安康;- - - - - - - - - - -,- - - - - - - - - - -,- - - - - - - - - - -
,,,,,7782,CLARK ,,,,,经理,,,,,,7839,1981/06/09 就是,,,,,2450,,,,,10
,,,,,7839,KING ,,,,,, PRESIDENT ,,1981/11/17 就是,,,,,5000,,,,,10
,,,,,7934,MILLER ,,,,职员,,,,,,7782,1982/01/23 就是,,,,,1300,,,,,10 当后面的表达式为真时,则返回行,否则跳过改行。
完成,select *,得到emp where ename=巴酢?
,,,,EMPNO ENAME ,,,,,工作,,,,,,,MGR hiredate,,,,,,萨尔通讯DEPTNO
- - - - - - - - - - -,- - - - - - - - - - -,- - - - - - -安康;- - - - - - - - - - -,- - - - - - - - - - - - - - - - - -安康;- - - - - - - - - - -,- - - - - - - - - - -,- - - - - - - - - - -
,,,,,7839,KING ,,,,,, PRESIDENT ,,1981/11/17 就是,,,,,5000,,,,,10 字符串是大小写敏感的
完成,select *,得到emp where ename=巴酢?
no rows 选择 条件表达式支持的比较操作符有如下
完成,select *,得到emp where sal<2000;
,,,,EMPNO ENAME ,,,,,工作,,,,,,,MGR hiredate,,,,,,萨尔通讯DEPTNO
- - - - - - - - - - -,- - - - - - - - - - -,- - - - - - -安康;- - - - - - - - - - -,- - - - - - - - - - - - - - - - - -安康;- - - - - - - - - - -,- - - - - - - - - - -,- - - - - - - - - - -
,,,,,7369,SMITH ,,,,,职员,,,,,,7902,1980/12/17 就是,,,,,,800,,,,,20
,,,,,7499,ALLEN ,,,,,销售员,,,,,,7698,1981/02/20 就是,,,,,1600,300,,,,,30岁
,,,,,7521,WARD ,,,,,,销售员,,,,,,7698,1981/02/22 就是,,,,,1250,500,,,,,30岁
,,,,,7654,MARTIN ,,,,销售员,,,,,,7698,1981/09/28 就是,,,,,1250年1400,,,,,30岁
,,,,,7844,TURNER ,,,,销售员,,,,,,7698,1981/09/08 就是,,,,,1500,,,0,,,,,30岁
,,,,,7876,ADAMS ,,,,,职员,,,,,,7788,1987/05/23 就是,,,,,1100,,,,,20
,,,,,7900,JAMES ,,,,,职员,,,,,,7698,1981/12/03 就是,,,,,,950,,,,,30岁
,,,,,7934,MILLER ,,,,职员,,,,,,7782,1982/01/23 就是,,,,,1300,,,,,10 之间,只要值在这个范围内,就返回值
完成,select *,得到emp where sal 结构;1500年,以及2000;
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