CREATE TABLE t1 ( id int, [date] datetime NULL ) CREATE TABLE t2 ( id int, [date] datetime NULL ) INSERT INTO t1 ([id], [date]) VALUES (1, NULL), (1, NULL), (2, NULL), (2, NULL), (3, NULL) INSERT INTO t2 ([id], [date]) VALUES (1, '2001-01-01'), (1, '2001-01-02'), (2, '2001-01-03'), (2, '2001-01-04'), (3, '2001-01-05') SELECT * FROM t1 SELECT * FROM t2 SELECT * FROM (SELECT *, ROW_NUMBER() OVER (PARTITION BY id ORDER BY [date]) AS rno FROM t1) AS t INNER JOIN (SELECT *, ROW_NUMBER() OVER (PARTITION BY id ORDER BY [date]) AS rno FROM t2) AS tt ON t.id = tt.id AND t.rno = tt.rno UPDATE t SET t.[date] = tt.[date] FROM (SELECT *, ROW_NUMBER() OVER (PARTITION BY id ORDER BY [date]) AS rno FROM t1) AS t INNER JOIN (SELECT *, ROW_NUMBER() OVER (PARTITION BY id ORDER BY [date]) AS rno FROM t2) AS tt ON t.id = tt.id AND t.rno = tt.rno SELECT * FROM (SELECT *, ROW_NUMBER() OVER (PARTITION BY id ORDER BY [date]) AS rno FROM t1) AS t INNER JOIN (SELECT *, ROW_NUMBER() OVER (PARTITION BY id ORDER BY [date]) AS rno FROM t2) AS tt ON t.id = tt.id AND t.rno = tt.rno