如何将两个表与内部联接组合并计算一些列

Question

我有两张桌子。

players: Username, Gang, Cash, Bank
gang: gangId, gangName

我想选择所有的帮派，并检查有多少玩家拥有与帮派相同的帮派ID，并将其作为total_members。我还想让它为该团伙的所有成员梳理现金和银行，并将其作为total_wealth。我怎么能这样做？

Answer 1

select g.gangid, 
       count(p.username) as total_members, 
       sum(cash+bank) as total_wealth
from gang g
left join players p on p.gang = g.gangid
group by g.gangid

Answer 2

这样的事情：

    SELECT p.gang, count(gang)
    FROM players p
    GROUP BY p.gang

目前还不清楚名为＆＃34; gang＆＃34;是ID还是名称。这是假设它是ID。

Answer 3

即使它们可能很慢，这些也应该接近您想要的效果：

SELECT gang.gangId From gang left join Players ON gang.gangId = Players.gang

SELECT SUM(cash + bank) from Players.gang where gang = gangId