Question

是否可以将我的sql SELECT语句的结果分组，而无需在一个语句中创建临时表并对其进行分组？我有一张表，可以节省信用卡号和借方帐号的借方和贷方金额。并且为相反的字段放零，我用下面的union select语句做了第一个grouppage我需要根据重复的帐户名称求和我可以很容易地得到这个或者必须加载临时表吗？我的选择陈述如下

select  journal_drname  AS ACCNAME, sum(amount) AS DEBT,0 as CREDIT
FROM JOURNAL GROUP BY journal_drname 
 UNION select  journal_crname  AS ACCNAME, 0 as DEBT,sum(amount) AS   
 CREDIT,
 FROM JOURNAL GROUP BY journal_crname

返回如下数据：

ACCNAME      DEBIT     CREDIT
--------   -------     ------
CASH        0           1,000
CASH        900          0
CASH        300          0
BANK        200          0
BANK        400          0

我可以在上面进行总结，分组如下：

ACCNAME      DEBIT     CREDIT
--------   -------     ------
CASH        200          0
BANK        600          0

我想加入上述结果。

我试图避免使用临时表，但如果这是实现此目的的唯一实用方法，我想了解更多关于以这种方式使用临时表的信息。

我也试过做某种加入和联合，但不满足条件，我也无法弄清楚如何做到这一点。

Answer 1

如果每个子查询只需要一行，则删除group by：

select  'CASH' as ACCNAME, sum(amount) AS DEBT, 0 as CREDIT
FROM JOURNAL 
UNION ALL
select  'BANK' as ACCNAME, 0 as DEBT, sum(amount) AS  CREDIT
FROM JOURNAL;

（注意：ACCNAME值可能会反转。）

重要提示：您应该使用UNION ALL来进行此类查询，而不是UNION。除非您打算删除重复项，否则没有理由承担删除重复项的开销。

此外，您的原始查询应该有效，除非accname字段中有异常字符。

Answer 2

正如您所说的查询有效，我们可以将您的联合查询称为表

( ...... ) myTable

然后创建一个子查询以获得最后一步

SELECT ACCNAME,
       CASE WHEN SUM(CREDIT - DEBT) < 0 THEN - SUM(CREDIT - DEBT)
            ELSE 0
       END DEBT,
       CASE WHEN SUM(CREDIT - DEBT) > 0 THEN   SUM(CREDIT - DEBT)
            ELSE 0
       END CREDIT
FROM ( ...... ) myTable
GROUP BY ACCNAME

Answer 3

怎么样：

select ACCNAME, 
    CASE WHEN sum(DEBT)>sum(CREDIT) THEN sum(DEBT)-sum(CREDIT) ELSE 0 AS DEBT, 
    CASE WHEN sum(DEBT)<sum(CREDIT) THEN sum(CREDIT)-sum(DEBT) ELSE 0 AS CREDIT 
FROM (
    select  journal_drname  AS ACCNAME, 
        sum(amount) AS DEBT,
        0 as CREDIT
    FROM JOURNAL GROUP BY journal_drname 
UNION 
    select journal_crname  AS ACCNAME, 
        0 as DEBT,
        sum(amount) AS CREDIT,
 FROM JOURNAL GROUP BY journal_crname
) group by ACCNAME

嵌套联合选择语句

3 个答案: