[sql查询] 重复数据只取一条

SELECT * FROM  tab_init
WHERE id IN 
( 
--根据Data分类获取数据最大ID列表 
select max(id) from tab_init
group by a,b
)

 先找出重复数据的 最大的Id ( group by 后面可跟多列, 根据规则找到重复数据), 取出 id 最大或最小的 Id, 然后使用 in查询,就可以得到不重复的数据

配合 With .. As () 非常方便

 --tab_jcxh_CertificateInfoAbility_New导入最新数据
 go

 with  tab_init
  
 as  
   (
      select ROW_NUMBER() over (order by OperateTime) as Id,* from  [Person].tab_jcxh_CertificateInfoAbility
   )

  insert into [Person].tab_jcxh_CertificateInfoAbility_New(IndexId,CertificateNumber,ItemCode,ItemName,CertificateDeadline,zzType,IsOperate,OperateTime)
 SELECT IndexId,CertificateNumber,ItemCode,ItemName,CertificateDeadline,zzType,IsOperate,OperateTime  FROM  tab_init
WHERE id IN 
( 
--根据Data分类获取数据最大ID列表 
select max(id) from tab_init
group by CertificateNumber
)