Sql语句——limit、inner join（内部连接） left join （左链接）

SELECT * FROM championship WHERE championshipState=0 AND championshipId IN(
SELECT championshipTeamChampionshipId FROM championship_team WHERE championshipTeamState=0 AND championshipTeamTeamId=(
SELECT userBelongToMainTeam FROM users WHERE userState=0 AND usersId=1)) LIMIT 0,5

limit 好像是用来限制几条数据的，加一个ORDER BY 的排序

select group_concat(mu.username),GROUP_CONCAT(mu.usersId) as members,ta.teamId,ta.teamName,tb.teamId,tb.teamName from (
select * from match_member as m inner join users as u on m.matchMemberUserId=u.usersId
inner join match on match.matchId = m.matchMemberMatchId
inner join (
select match.matchId as id from match where match.teamA=6 or match.teamB=6 ORDER BY match.matchTime desc limit 0,5
) as malimit on malimit.id = m.matchMemberMatchId
) as mu
inner join match as m on m.matchId=mu.matchMemberMatchId
INNER JOIN team as ta on ta.teamId =m.teamA
inner join team as tb on tb.teamId = m.teamB
group by ta.teamId,tb.teamId

GROUP_CONCAT：来自一个组的连接——以逗号的形式连接起来。注意不能为空
也就是UserID之间的所有数据放在一个列下面，用，连接
group_concat(town)
长沙,北京,北京,