问题
I want to delete duplicate rows based on two columns but need to keep 1 row all of them.
Duplicate rows can be more than two rows like,
ID NAME PHONE
-- ---- ----
1 NIL 1234
2 NIL 1234
3 NIL 1234
4 MES 5989
I want to delete any of 2 rows from above 3 and keep 1 row.
回答1:
DELETE a
FROM tableA a
LEFT JOIN
(
SELECT MIN(ID) ID, Name, Phone
FROM TableA
GROUP BY Name, Phone
) b ON a.ID = b.ID AND
a.NAme = b.Name AND
a.Phone = b.Phone
WHERE b.ID IS NULL
- SQLFiddle Demo
After you have executed the delete statement, enforce a unique constraint on the column so you cannot insert duplicate records again,
ALTER TABLE TableA ADD CONSTRAINT tb_uq UNIQUE (Name, Phone)
回答2:
DELETE
FROM Table
WHERE Table.id NOT IN (
SELECT MIN(idTable) idtable
FROM idTable
GROUP BY name, phone)
来源：https://stackoverflow.com/questions/15548655/delete-duplicate-rows-and-need-to-keep-one-from-all-of-them-in-mysql