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1.分頁查詢 select count(*) times,title from menulog group by title order by count(*) desc 
2, 生成一個帶rn字段的表tableRN=(SELECT rownum as rn, a.* FROM (select count(*) times,title from menulog group by title order by count(*) desc ) a)
3 select * from tableRN where rn between 0 and 6
select * from(SELECT rownum as rn, a.* FROM (select count(*) times,title from menulog group by title order by count(*) desc ) a)
where rn between 0 and 6
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select count(*) times,max(url), title from menulog b group by title order by count(*) desc
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今天看公司的代碼，看到很多max或者sum某個字段的值這樣無意義的寫法，一開始很疑惑這樣寫是為了什么。
后來了解到，原來和后面使用到的group by有關，只要select的，不調用聚合函數的，一定要出現在group by里，而group by里出現的，不一定在出現在select里。
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