@PeterClemmensen , many thanks for your kind reply. Yes, it works, and seems the hash object is more efficient. The situation is a bit more complicated. There are three tables: A is target table, B and C are reference table. Table A: ID1 ID2 Val1 Val2 Val3 1 b 12 15 18 3 dd 13 16 19 4 c 14 17 11 Table b ID1 ID2 Val1 Val2 Val3 1 e 23 22 27 3 d 24 21 26 4 cc 25 28 25 Table c ID1 ID2 ID3 1 e b 3 d dd 4 c ccc Results: ID1 ID2 Val1 Val2 Val3 1 b 23 22 27 3 dd 24 21 26 4 c 14 17 11 Because in table C, in column ID2 and ID3, e and b are identical ID, same for d and dd so first two columns (ID1 =1 and ID1=3) are replaced by the new value of Val1 val2 and val3. Sorry about this, but the datatable I am dealing with is a bit chaotic. How to solve this using hash object? or other alternatives? Many thanks in advance.
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