delete glt_entity_tmp from glt_entity_tmp,(select idd from glt_entity_tmp group by nam having count(*) > 1 ) as t2
二、以二個或以上字段來唯一確定一條記錄，可以用以下SQL來刪除，但要注意每條記錄中必須有第三個字段來唯一確定這條記錄（使用max刪除）
delete gbi_pd_theme_new_tmp from gbi_pd_theme_new_tmp,(select new_code,the_code,max(the_new_code) as the_new_code from gbi_pd_theme_new_tmp group by new_code,the_code having count(*) > 1) as t2
where gbi_pd_theme_new_tmp.new_code=t2.new_code and gbi_pd_theme_new_tmp.the_code=t2.the_code and gbi_pd_theme_new_tmp.the_new_code=t2.the_new_code
注意：如果是有多于2條重復的記錄，要執行多次
因為此例子中每條記錄有一個唯一的字段the_new_code，所以可以用max來刪除重復記錄
