group by 字句的擴展+rollup字句+cube字句+grouping（）函數

1rollup字句 rollup字句擴展group by字句，爲每一個分組返回一條小計記錄，併爲全部分組返回總計 列如：rollup字句獲取每個部門的工資總計 select d.dname,sum(e.sal) from emp e,dept d where e.deptno=d.deptno group by rollup(d.dname) order by d.dname; 解釋： dname

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