Question

假设我有一张看起来像这样的表：

-------------------------------
id|column2|column3   |column4
-------------------------------
1  value1  somevalue  somevalue
2  value2  somevalue  somevalue
3  value2  somevalue  somevalue <----- I want this column deleted
4  value3  somevalue  somevalue

如您所见，我想删除当前行和上一行在column2中具有相同值的行。

Answer 1

我会尝试像

这样的东西

DELETE FROM Table t1 
WHERE EXISTS (SELECT 1 from Table t2 
              WHERE t1.Column2 = t2.Column2 
              AND t2.Id + 1 = t1.Id)

对于您的特定查询，我会使用t2.Id + 1 = t1.Id而不是t2.Id < t1.Id，因为这会删除任何出现，而不是仅连续的条目。

Answer 2

DELETE FROM Table t1
WHERE EXISTS (SELECT 1 from Table t2
              WHERE t1.Column2 = t2.Column2
              AND t1.Column3 = t2.Column3                  
              AND t1.Column4 = t2.Column4
              AND t2.Id > t1.Id)

如果您需要仅按一个字段比较行

DELETE FROM Table t1
WHERE EXISTS (SELECT 1 from Table t2
              WHERE t1.Column2 = t2.Column2
              AND t2.Id > t1.Id)

Answer 3

delete from table_name where rowid in(
select a.rowid 
from (
      select rowid,
            row_number() over (partition by column_name_having_duplicates order by                  column_name_having_duplicates)rnk 
from table_name a
)a
where a.rnk>1);

如果前一个在特定列中具有相同值，则如何删除行

3 个答案: