试图获得：
trans_id | qty | ptotal
---------------------------
100 | 30 | 2
101 | 25 | 0
从inv表
trans_id | pull_from_trans | trans_desc | qty | itc_part_id
---------------------------------------------------------------
100 | null | rec | 30 | 1003
101 | null | rec | 25 | 1010
102 | 100 | pull | 1 | 1003
103 | 100 | pull | 1 | 1003
使用（但不起作用）
SELECT tb1.trans_id, tb1.qty,sum(tb2.qty) as ptotal
FROM inv tb1 where tb1.trans_desc='rec'
INNER JOIN inv tb2 ON tb1.trans_id=tb2.pull_from_trans
WHERE tb2.trans_desc='pull' GROUP BY tb2.pull_from_trans
最佳答案
您在那里有两个where子句。将第一个验证作为AND放在最后的WHERE子句中：
SELECT tb1.trans_id, tb1.qty, sum(tb2.qty) AS ptotal
FROM inv tb1
INNER JOIN inv tb2 ON tb1.trans_id = tb2.pull_from_trans
WHERE tb2.trans_desc = 'pull' AND tb1.trans_desc = 'rec'
GROUP BY tb2.pull_from_trans
不太确定您的GROUP BY。我可能会这样做：
GROUP BY tb1.trans_id, tb1.qty，如果您要的是tb1.qty，但是请查看它是否能满足您的需求。关于mysql - MYSQL-合并来自同一表的多个查询，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/20126689/