Let's say I have a table that looks something like this:
------------------------------- 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 As you can see I want to delete the rows where the current and the previous row have the same value in column2.
I would try something like
DELETE FROM Table t1 WHERE EXISTS (SELECT 1 from Table t2 WHERE t1.Column2 = t2.Column2 AND t2.Id + 1 = t1.Id) For your specific query, I would use the t2.Id + 1 = t1.Id instead of t2.Id < t1.Id as this would delete for any occurances, not consecutive entries only.
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) OR if you need compare rows just by one field
DELETE FROM Table t1 WHERE EXISTS (SELECT 1 from Table t2 WHERE t1.Column2 = t2.Column2 AND t2.Id > t1.Id) 
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); 
