使用MinID和Complex Select从MYsql表中删除重复项

Question

I found this here to delete records with min ID:

DELETE FROM Table WHERE id NOT IN (SELECT MIN(id) FROM Table GROUP BY FieldA)

However I don't want all the found dupes in the table to have the one with the lower ID removed, only a subset of them. I have other criteria for other dupes patterns. So I made my select to get the subset of records that have dupes AND other conditions where I then DO want the min ids removed:

Select min(Z),Max(Z),count(*) from Table  
group by P,N
having count(*)>1 and Min(Z)!=Max(Z) and Min(Z)>0 

I am unclear how to first get that subset of records and THEN remove the minID from the dupes in that subset

Answer 1

In MySQL use LEFT JOIN :

delete t
    from table t left join
         (Select min(Z), Max(Z), count(*) 
          from Table  
          group by P, N
          having count(*) > 1 and Min(Z) <> Max(Z) and Min(Z) > 0
         ) tt
         on t.? = tt.?
    where tt.? is null; 

It is unclear how the id is defined in your expression. It is also unclear whether the subquery generates the ids to keep or to delete. The version above assumes it is generating the ids to keep. (If it generates the ids to delete, then use inner join and get rid of the where clause.)