Question

Original table

+-- Col 1 --+-- Col 2 --+
+--   1   --+--   a   --+
+--   1   --+--   b   --+
+--   1   --+--   c   --+
+--   2   --+--   d   --+
+--   3   --+--   e   --+
+--   3   --+--   f   --+
+-----------------------+

Result :

+-- Col 1 --+-- Col 2 --+
+--   1   --+--   a   --+
+--   2   --+--   d   --+
+--   3   --+--   e   --+
+-----------------------+

Any idea how to distinct the table?

Answer 1

“DISTINCT” applies to every column in the result set.

A “GROUP BY” will provide the result you require, but you need to think about whether “col2” has any real meaning in your result set.

 SELECT col1, min(col2) as col2
      FROM T
     GROUP BY col1