Grouping Result

Here's my query:

SELECT col_1, col_2, col_3, col_4 FROM my_table
WHERE (col_1 = @.col_1) AND (col_2 = @.col_2)
ORDER BY col_1

I want my result rows to have an uniqe value in col_3. How can I exclude rows (but one) that have the same value in col_3?

Thanx

/sf

SELECT TOP 1 col_1, col_2, col_3, col_4 FROM my_table
WHERE (col_1 = @.col_1) AND (col_2 = @.col_2)
ORDER BY col_1

|||Thank you for your answer.

But will not this query only output one row?

I'll try to explain my problem better:

Here's my query:

SELECT col_1, col_2, col_3, col_4 FROM my_table
WHERE (col_1 = @.col_1) AND (col_2 = @.col_2)
ORDER BY col_1

What I want is output all rows with unique value in col_3 and if several rows have the same value in col_3, I only want one of those rows. The following could have worked, but it's not valid sql:

SELECT col_1, col_2, col_3, col_4 FROM my_table
WHERE (col_1 = @.col_1) AND (col_2 = @.col_2)
ORDER BY col_1
GROUP BY col_3|||SELECT MAX(col_1), MAX(col_2), col_3, MAX(col_4) FROM my_table
WHERE (col_1 = @.col_1) AND (col_2 = @.col_2)
ORDER BY MAX(col_1)
GROUP BY col_3

I used MAX() for the non-grouped values, but you could use MIN(), SUM(), AVG()