Oracle分组函数之ROLLUP的基本用法

rollup函数

本博客简单介绍一下oracle分组函数之rollup的用法，rollup函数常用于分组统计，也是属于oracle分析函数的一种

环境准备

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									create table dept as select * from scott.dept;

									create table emp as select * from scott.emp;

业务场景：求各部门的工资总和及其所有部门的工资总和

这里可以用union来做，先按部门统计工资之和，然后在统计全部部门的工资之和

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									select a.dname, sum(b.sal)

									 from scott.dept a, scott.emp b

									 where a.deptno = b.deptno

									 group by a.dname

									union all

									select null, sum(b.sal)

									 from scott.dept a, scott.emp b

									 where a.deptno = b.deptno;

上面是用union来做，然后用rollup来做，语法更简单，而且性能更好

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									select a.dname, sum(b.sal)

									 from scott.dept a, scott.emp b

									 where a.deptno = b.deptno

									 group by rollup(a.dname);

Oracle分组函数之ROLLUP的基本用法

业务场景：基于上面的统计，再加需求，现在要看看每个部门岗位对应的工资之和

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									select a.dname, b.job, sum(b.sal)

									 from scott.dept a, scott.emp b

									 where a.deptno = b.deptno

									 group by a.dname, b.job

									union all//各部门的工资之和

									select a.dname, null, sum(b.sal)

									 from scott.dept a, scott.emp b

									 where a.deptno = b.deptno

									 group by a.dname

									union all//所有部门工资之和

									select null, null, sum(b.sal)

									 from scott.dept a, scott.emp b

									 where a.deptno = b.deptno;

用rollup实现，语法更简单

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									select a.dname, b.job, sum(b.sal)

									 from scott.dept a, scott.emp b

									 where a.deptno = b.deptno

									 group by rollup(a.dname, b.job);

Oracle分组函数之ROLLUP的基本用法

假如再加个时间统计的，可以用下面sql：

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									select to_char(b.hiredate, 'yyyy') hiredate, a.dname, b.job, sum(b.sal)

									 from scott.dept a, scott.emp b

									 where a.deptno = b.deptno

									 group by rollup(to_char(b.hiredate, 'yyyy'), a.dname, b.job);

cube函数

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									select a.dname, b.job, sum(b.sal)

									 from scott.dept a, scott.emp b

									 where a.deptno = b.deptno

									 group by cube(a.dname, b.job);