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SQL 连接查询练习

时间:2017-11-07 19:45:27      阅读:232      评论:0      收藏:0      [点我收藏+]

标签:语句   语法   部门   name   左外连接   工资   连接   using   upper   

                                          --连接查询练习
                                          --内连接
--返回有部门的员工工资和奖金
--92 语法
SELECT  n.ename, n.sal, n.comm, d.deptno, d.dname
FROM new_emp n, dept d
WHERE n.deptno = d.deptno;
--99 语法
SELECT  n.ename, n.sal, n.comm, d.deptno, d.dname
FROM new_emp n INNER JOIN dept d          --可以省略 INNER
ON n.deptno = d.deptno;
--或使用 JOIN...USING() 语句
SELECT  n.ename, n.sal, n.comm, deptno, d.dname
FROM new_emp n JOIN dept d          
USING(deptno);
--------------------------------------------------------------------------------------------------------
                                          --外连接(两表连接)
--叉集(笛卡尔集)
SELECT  n.ename, n.sal, n.comm, d.deptno, d.dname
FROM new_emp n CROSS JOIN dept d;
                                   
--没有部门的员工也返回(主表为员工表)
--92 语法
SELECT  n.ename, n.sal, n.comm, d.deptno, d.dname
FROM new_emp n, dept d
WHERE n.deptno = d.deptno(+);
--99 语法(右外连接)
SELECT  n.ename, n.sal, n.comm, d.deptno, d.dname
FROM  dept d RIGHT OUTER JOIN new_emp n
ON n.deptno = d.deptno;

--没有员工的部门也返回(主表为部门表)
--92 语法
SELECT  n.ename, n.sal, n.comm, d.deptno, d.dname
FROM new_emp n, dept d
WHERE n.deptno(+) = d.deptno;
--99 语法 (左外连接)
SELECT  n.ename, n.sal, n.comm, d.deptno, d.dname
FROM  dept d LEFT  JOIN new_emp n         --可以省略OUTER
ON n.deptno = d.deptno;

--既返回无部门的员工股,也返回无员工的部门
--92 语法不能两边都写 (+)
SELECT  n.ename, n.sal, n.comm, d.deptno, d.dname
FROM new_emp n, dept d
WHERE n.deptno(+) = d.deptno(+);          --该行报错
--99 语法(满外连接)
SELECT  n.ename, n.sal, n.comm, d.deptno, d.dname
FROM  dept d FULL OUTER JOIN new_emp n
ON n.deptno = d.deptno;
---------------------------------------------------------------------------------------------------------
                                          --外连接(三表连接)
--查询所有借书记录(不存在的学生和不存在的书均显示)
SELECT r.borrow_id, t.stu_id, t.stu_name, b.book_id, UPPER(b.book_name)
FROM student t, book b, borrow r
WHERE r.stu_id = t.stu_id(+) AND
              r.book_id = b.book_id(+)
ORDER BY r.borrow_id;

--只显示不存在的书
SELECT r.borrow_id, t.stu_id, t.stu_name, b.book_id, UPPER(b.book_name)
FROM student t, book b, borrow r
WHERE r.stu_id = t.stu_id       AND
              r.book_id = b.book_id(+)
ORDER BY r.borrow_id;

--只显示不存在的学生
SELECT r.borrow_id, t.stu_id, t.stu_name, b.book_id, UPPER(b.book_name)
FROM student t, book b, borrow r
WHERE r.stu_id = t.stu_id(+) AND
              r.book_id = b.book_id
ORDER BY r.borrow_id;

--书和学生必须都存在
SELECT r.borrow_id, t.stu_id, t.stu_name, b.book_id, UPPER(b.book_name)
FROM student t, book b, borrow r
WHERE r.stu_id = t.stu_id      AND
              r.book_id = b.book_id
ORDER BY r.borrow_id;

 

SQL 连接查询练习

标签:语句   语法   部门   name   左外连接   工资   连接   using   upper   

原文地址:http://www.cnblogs.com/edwardli/p/7800215.html

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