Find and remove duplicate rows by two columns

Question

I read all the relevant duplicated questions/answers and I found this to be the most relevant answer:

INSERT IGNORE INTO temp(MAILING_ID,REPORT_ID) 
SELECT DISTI         


        

Answer 1

The best way to delete duplicate rows by multiple columns is the simplest one:

Add an UNIQUE index:

ALTER IGNORE TABLE your_table ADD UNIQUE (field1,field2,field3);

The IGNORE above makes sure that only the first found row is kept, the rest discarded.

(You can then drop that index if you need future duplicates and/or know they won't happen again).