为什么我用了order by,在最后select出来的结果中,相同的记录会出现两次。代码是这样的。
SELECT *, tid AS Expr1, title AS Expr2
FROM dnt_topics
WHERE (fid = 19)
ORDER BY tid
这个表是discuz!nt的,我怀疑他是不是加了什么措施才会这样。
SELECT *, tid AS Expr1, title AS Expr2
FROM dnt_topics
WHERE (fid = 19)
ORDER BY tid
这个表是discuz!nt的,我怀疑他是不是加了什么措施才会这样。
FROM dnt_topics
WHERE (fid = 19)
ORDER BY tid
FROM dnt_topics
WHERE (fid = 19)
ORDER BY tid
order by 只是排序而已,可以通过distinct来过滤重复的记录
SELECT distinct *, tid AS Expr1, title AS Expr2
FROM dnt_topics
WHERE (fid = 19)
ORDER BY tid
你要是想筛选数据,就该使用SELECT distinct *, tid AS Expr1, title AS Expr2
FROM dnt_topics
WHERE (fid = 19)
ORDER BY tid