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  • sql group句子

    rollup
    
    SELECT employee_id,department_id,job_id,SUM(salary)
    
    FROM   employees
    
    WHERE  department_id <60
    
    GROUP  BY ROLLUP (department_id,job_id,employee_id);
    
     执行n+1次分组然后union,顺序是employee_id;job_id;department_id;空一共四次(从右至左每次以一个分组最后不分组求一次总和)
    
     
    
     
    
    nothing
    
    SELECT employee_id,department_id,job_id,SUM(salary)
    
    FROM   employees
    
    WHERE  department_id <60
    
    GROUP  BY department_id,job_id,employee_id;
    
    按顺序检测,先按department_id分组计算然后一个部门的然后这个部门内job_id分组计算一次然后employee_id再分组计算一次,然后接着下一个部门分组……..执行下去 注:每次三个都同时被gruoping了
    
     
    
     
    
    cube
    
    SELECT employee_id,department_id,job_id,SUM(salary)
    
    FROM   employees
    
    WHERE  department_id <60
    
    GROUP  BY CUBE (department_id,job_id,employee_id);
    
    执行2的n次方次分组计算,排列组合;一般用的时候都带order by排序确定谁先显示
    
     
    
     
    
    Grouping
    
    以使用Grouping 函数; 没有被Grouping到返回1,否则返回0
    
    SELECT employee_id,department_id,job_id,SUM(salary),GROUPING(employee_id),GROUPING(department_id),GROUPING(job_id)
    
    FROM employees
    
    WHERE department_id < 60
    
    GROUP BY department_id,job_id,employee_id;
    
     
    
    SELECT employee_id,department_id,job_id,SUM(salary),GROUPING(employee_id),GROUPING(department_id),GROUPING(job_id)
    
    FROM employees
    
    WHERE department_id < 60
    
    GROUP BY ROLLUP (department_id,job_id,employee_id);
    
     
    
    SELECT employee_id,department_id,job_id,SUM(salary),GROUPING(employee_id),GROUPING(department_id),GROUPING(job_id)
    
    FROM employees
    
    WHERE department_id < 60
    
    GROUP BY CUBE (department_id,job_id,employee_id);
    
     
    
    GROUPING SETS
    
    使用Grouping Set 来代替多次UNION
    
    SELECT department_id,job_id,manager_id,AVG(salary)
    
    FROM   employees
    
    GROUP  BY GROUPING SETS ((department_id,job_id),(job_id,manager_id));
    
    相当于
    
    SELECT department_id,job_id,manager_id,AVG(salary)
    
    FROM   employees
    
    GROUP  BY  (department_id,job_id);
    
    UNION
    
    SELECT department_id,job_id,manager_id,AVG(salary)
    
    FROM   employees
    
    GROUP  BY GROUPING SETS (job_id,manager_id);
    

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  • 原文地址:https://www.cnblogs.com/wanghang/p/6299534.html
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