我做了一次group by,这样sum()就可以正常工作了。SELECT sum(a.x), sum(b.y) FROM a,b GROUP BY a.n where a.n=b.m
到目前为止,这工作得很好,但问题是,我需要为第二个和(sum(b.y))与第一个和(sum(a.x))进行不同的分组。这就是我实际尝试选择的sum(stock.amount) - if( sold.amount IS NULL , 0, sum( sol
我正在努力区分,然后找出一个球员在任何一个赛季中所效力的球队的数量,以及他为之效力的球队的数量。这是绊倒我,当然,我有一个样本以下(第二)一个。第一个是我失败的尝试(SELECT id, year, team FROM battingORDER BY id DESC0.id =b.id;
GROUP BY id,year,team
ORDER B
error note:Error : You have an error in your SQL syntax; check the manual that corresponds to your MySQLserver version for the right syntax to use near '@sum int default 0; if @sum>1 then
' at line