Question

我写了一个SQL语句来显示department_id，job_id和薪水最低的员工，但其中一个条件要求我排除名称为'IT'和'SALES'的部门，这些部门只能从另一个表部门。因此，我使用共享列department_id加入了两个表，并设法根据需要过滤结果，但是，我无法选择department_id与job_id和工资一起显示。这就是我到目前为止所做的：

 SELECT EMPLOYEES.DEPARTMENT_ID JOB_ID, MIN(SALARY)
 FROM EMPLOYEES JOIN DEPARTMENTS
 ON DEPARTMENTS.DEPARTMENT_ID = EMPLOYEES.DEPARTMENT_ID
 WHERE JOB_ID NOT LIKE '%REP'
 AND DEPARTMENTS.DEPARTMENT_NAME NOT IN ('IT','SALES')
 GROUP BY EMPLOYEES.DEPARTMENT_ID
 HAVING MIN(SALARY) >= 6000 AND MIN(SALARY) <= 18000;

Answer 1

首先，表别名使查询更容易编写和读取：

 SELECT e.DEPARTMENT_ID, e.JOB_ID, MIN(e.SALARY)
 FROM EMPLOYEES e JOIN
      DEPARTMENTS d
      ON d.DEPARTMENT_ID = e.DEPARTMENT_ID
 WHERE e.JOB_ID NOT LIKE '%REP' AND d.DEPARTMENT_NAME NOT IN ('IT',' SALES')
 GROUP BY e.DEPARTMENT_ID, e.JOB_ID
 HAVING MIN(e.SALARY) >= 6000 AND MIN(e.SALARY) <= 18000;

您需要GROUP BY中的所有非汇总列。

Answer 2

SELECT中的部门ID后，查询中缺少逗号 - 因此它将部门ID的作业ID视为别名，并在查询结果中显示为作业ID。但是，您再次在GROUP BY子句中没有作业ID，需要在组中添加或必须使用任何聚合函数

  SELECT **EMPLOYEES.DEPARTMENT_ID, JOB_ID,** MIN(SALARY)
  FROM EMPLOYEES JOIN DEPARTMENTS ON DEPARTMENTS.DEPARTMENT_ID=EMPLOYEES.DEPARTMENT_ID
  WHERE JOB_ID NOT LIKE '%REP' AND DEPARTMENTS.DEPARTMENT_NAME NOT IN('IT','SALES')
  GROUP BY EMPLOYEES.DEPARTMENT_ID,JOB_ID
  HAVING MIN(SALARY) >= 6000 AND MIN(SALARY) <= 18000;

SQL：无法选择已加入的列

2 个答案: