基本查询语句
-- 实验四 数据库SQL语言基础编程
-- 实验目的：
-- 掌握数据库查询语句的编写方法
-- 掌握利用查询语言完成基本查询
-- 掌握利用SQL语句完成数据的添加、删除、修改操作
-- 实验内容：
-- 一、简单查询
-- 编写简单查询语句，理解笛卡尔积、选择、投影的概念及其在SQL中的实现
-- 查询员工表与部门表的笛卡尔积
select empno,ename,dname
from emp,dept
where emp.deptno=dept.deptno;
-- 在上述操作的基础上完成连接的选择操作和投影操作
select empno,ename,dname
from emp
JOIN dept ON emp.deptno=dept.deptno;
select empno,ename,dname
from EMP
LEFT JOIN dept ON emp.deptno=dept.deptno;
select empno,ename,dname
from emp
RIGHT JOIN dept ON emp.deptno=dept.deptno;
select empno,ename,dname
from emp
FULL JOIN dept ON emp.deptno=dept.deptno;
select count(empno),
dname
from emp
FULL JOIN dept ON emp.deptno=dept.deptno
GROUP BY emp.deptno,dname;
-- -- 对查询数据进行排序操作
select count(empno),
nvl(dname,'OTHER')
from emp
FULL JOIN dept ON emp.deptno=dept.deptno
GROUP BY emp.deptno,dname;
-- -- 编写查询语句，完成对员工信息、部门情况等的基本查询
-- -- 查询工资超过2500的员工基本信息
select * from emp where sal>2500
-- -- 查询月总收入超过2500的员工基本信息
select * from emp
where sal+nvl(comm,0) >2500;
-- -- 查询工资超过2500的员工的姓名及其所在部门名称
select empno,
ename,
sal,
nvl(comm,0) as comm,
sal+nvl(comm,0) incoming
from emp
where sal>2500
ORDER BY incoming desc,ename asc;
-- -- 查询所有员工的工资、奖金、总收入，并按部门编号排序
select empno,
ename,
sal,
comm,
sal+nvl(comm,0) incoming,
deptno
from emp
order by deptno;
-- -- 查询全公司的平均工资、最高工资、最低工资和总奖金数。
select sum(sal) sum_sal,
max(sal) max_sal,
min(sal) min_sal,
sum(sal+nvl(comm,0)) sum_incoming,
max(sal+nvl(comm,0)) max_incoming,
min(sal+nvl(comm,0)) min_incomingg
from emp;
-- -- 二、分组查询
-- -- 编写分组查询语句，理解分组查询的意义
select MAX(empno),
MIN(ename),
SUM(sal),
AVG(nvl(comm,0)) as avg_comm,
avg(sal+nvl(comm,0)) avg_incoming,
deptno
from emp
GROUP BY deptno
ORDER BY deptno;
-- -- 编写分组查询语句，实现分组查询的应用
select empno,
ename,
sal,
comm,
sal+nvl(comm,0) incoming,
deptno
from emp
ORDER BY deptno;
select MAX(empno),
MIN(ename),
SUM(sal),
AVG(nvl(comm,0)) as avg_comm,
avg(sal+nvl(comm,0)) avg_incoming,
deptno
from emp
where sal+nvl(comm,0)>2000
GROUP BY deptno
ORDER BY deptno;
select MAX(empno),
MIN(ename),
SUM(sal),
AVG(nvl(comm,0)) as avg_comm,
avg(sal+nvl(comm,0)) avg_incoming,
deptno
from emp
GROUP BY deptno
HAVING avg(sal+nvl(comm,0))>2000
ORDER BY deptno;
-- -- 三、增删改语句
-- -- 添加数据
insert into emp values(1234,'tang','teacher',null,'01-SEP-96',null,null,null);
insert into emp values(empno,ename,job,hiredate,sal) values(1234,'tang','teacher','01-SEP-96','980');
-- -- 修改数据
update emp set sal=1080 where empno=1234;
update emp set (sal=980,comm=100) where empno=1234;
-- -- 删除数据
delete from emp where empno=1234;
delete from emp where empno=20;
posted on 2018-11-30 09:43 努力努力的夏天 阅读(...) 评论(...) 编辑 收藏