我有以下sql
SELECT *, min(okd.position) FROM
-- all deals
(SELECT * FROM "Deals" as d
WHERE (d.active = true) AND (d.latitude BETWEEN 40 AND 41) AND (d.longitude BETWEEN -75 AND -70)) AS okd
LEFT JOIN
-- used deals
(SELECT * FROM "Deals" as ad INNER JOIN
(SELECT * FROM "DealsUsed" AS du WHERE du."CustomerId" = 1) AS rd
ON rd."DealId" = ad.id) as dd
--deals that were not used, grouped by user and sorted by position
ON dd."UserId" = okd."UserId" AND dd.position = okd.position
WHERE dd.id IS NULL
GROUP BY okd."UserId";
对我来说,它看起来像有效的SQL
SELECT *
的意思是“从FROM
条款中涉及的表格中给我所有列”。我认为它不仅仅是UserId,还包括其他一些列。哪个?不能说,因为你SELECT * FROM "Deals"
。考虑在任何地方避免使用SELECT *
,但需要快速和肮脏的测试目的。
因此,要么在GROUP BY
子句中枚举所有这些(你可能不想要),要么SELECT
只有UserId和聚合列;例如,
select okd."UserId", min(okd.position)
FROM (your current FROM clause)
group by okd."UserId"
[编辑,基于Oracle(正如我所知),但也适用于您的数据库]
看看下面的例子:
这项工作正常 - 我正在选择在这些部门工作的所有员工的部门编号和工资总额:
SQL> select deptno, sum(sal)
2 from emp
3 group by deptno
4 order by deptno;
DEPTNO SUM(SAL)
---------- ----------
10 8750
20 6775
30 9400
我也想包括工作,即每个部门和工作的工资总额。如果我在SELECT中包含一个新列但在GROUP BY中没有它,那么它将失败:
SQL> select deptno, job, sum(sal)
2 from emp
3 group by deptno
4 order by deptno;
select deptno, job, sum(sal)
*
ERROR at line 1:
ORA-00979: not a GROUP BY expression
因此,您有两种选择:
SQL> select deptno, job, sum(sal)
2 from emp
3 group by deptno, job
4 order by deptno, job;
DEPTNO JOB SUM(SAL)
---------- --------- ----------
10 CLERK 1300
10 MANAGER 2450
10 PRESIDENT 5000
20 ANALYST 3000
20 CLERK 800
20 MANAGER 2975
30 CLERK 950
30 MANAGER 2850
30 SALESMAN 5600
[多一点点]
还有一件事:有一种方法可以在不使用GROUP BY子句的情况下聚合值;在Oracle中,这就是分析函数的功能。我不知道你使用的数据库系统中是否有类似的东西,但你可能会检查它。这是一个例子:
SQL> select deptno, ename, job, sum(sal) over (partition by deptno) sum_sal_dept
2 from emp
3 order by deptno, job;
DEPTNO ENAME JOB SUM_SAL_DEPT
---------- ---------- --------- ------------
10 MILLER CLERK 8750
10 CLARK MANAGER 8750
10 KING PRESIDENT 8750
20 FORD ANALYST 6775
20 SMITH CLERK 6775
20 JONES MANAGER 6775
30 JAMES CLERK 9400
30 BLAKE MANAGER 9400
30 TURNER SALESMAN 9400
30 WARD SALESMAN 9400
30 ALLEN SALESMAN 9400
30 MARTIN SALESMAN 9400
看到?没有GROUP BY子句,我计算了每个部门的工资总和。