MySQL根据另一列总结一列

Question

我有一个相当标准的查询返回此表:

x  12  
y  59  
x  76  
x  35  
y  82  

我想分别对所有'x'值和所有'y'值求和.结果应该是这样的:

x  123  
y  141  

如果可以在MySQL中完成,我不想这样编程.我该怎么做呢？这是我的sql查询供参考:

SELECT
    tb1.val1,
    tb2.val2
FROM
    tb1 INNER JOIN tb2
ON
    tb1.id = tb2.id
WHERE
    (bunch of conditions unrelated to val1 and val2)
;

Answer 1

你正在寻找Group by和SUM聚合

select tb1.val1, sum(tb2.val2)
From tb1 INNER JOIN tb2
.....
Group by tb1.val1