如何为每个不同的column1值从（非唯一）column2中仅检索一条记录？

Question

RDBMS - Oracle 11g.

Question: I have a table like this -

column1   column2
A         111
A         222
A         333
B         444
C         555
C         666

I want to write a query that picks up just one record for each distinct column1 value. The output should be this way:

A         111
B         444
C         555

I am not worried about which value in corresponding column2 gets picked up. Only constraint is I just want a singe record being fetched for each of the distinct column1 value.

I cannot think of a way to do this without using procedures. Is this possible with just sql queries (no function/ procedure)? Thanks.

Answer 1

Sure

SELECT column1, MIN(column2)
  FROM your_table
 GROUP BY column1

Since you don't care which column2 value you get, you could also use MAX or many other aggregate functions instead of MIN .

Answer 2

If you don't care, let the column2 be MIN

  SELECT column1, 
         MIN(column2) 
    FROM table 
GROUP BY column1;

Answer 3

Select column1,MIN(column2)
From tableName
group by column1

SQL Fiddle Demo