两个独立表的总和 [英] Addition of the SUM of two independant tables

问题描述

我有两个桌子

td_sell

|----------|----------------|------------------|
|  id      |   user_id      |    price         |
|----------------------------------------------|
|  1       |      2         |     10           |
|----------------------------------------------|
|  2       |      1         |      5           |
|----------------------------------------------|
|  3       |      2         |      3           |
|----------------------------------------------|

和td_commsion

and td_commsion

|----------|----------------|------------------|
|  id      |   user_id      |    price         |
|----------------------------------------------|
|  1       |      1         |      3           |
|----------------------------------------------|
|  2       |      1         |      5           |
|----------------------------------------------|
|  3       |      2         |      3           |
|----------------------------------------------|

现在我想要这样的SQL查询

now i want a sql query like this

SELECT (SUM(td_sell.price) + SUM(td_comission.price)) AS his_earning
FROM td_sell, td_comission 
WHERE td_sell.user_id='1'
AND td_comission.user_id='1'

但显示异常结果

结果应为13，但显示为29

推荐答案

这将起作用:

SELECT (SELECT SUM(s.price) FROM td_sell s WHERE s.user_id = 1)
+
(SELECT SUM(c.price) FROM td_comission c WHERE c.user_id = 1)

演示: SqlFiddle

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