视图--bai

/*视图的必要性
create view population_all_view
as
select xxxx 详细信息 from qgck where rownum<500 -- sql语句不易读懂 create view population_all_view
as
select * from qgck where rownum<500;-- sql语句超出负载。 */ select * from scott.emp; --视图的创建
查询员工编号、员工名及所在部门的名称
create or replace view emp_basic_info_view
as
select scott.emp.empno as 员工编号,scott.emp.ename as 员工名,
scott.dept.dname as 部门名 from scott.emp ,scott.dept
where scott.emp.deptno = scott.dept.deptno --查询视图
select * from emp_basic_info_view delete from system.emp_basic_info_view where 员工编号='8000'; --练习1

  

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