Question

I tried to read about not a group by expression errors from some other posts, but all of them mention group functions such as MAX, MIN, etc. I’m not using any of it and it’s a really simple query returning this sort of error.

SELECT * 
FROM   ad_voarnet_atendimento_pista 
WHERE  is_closed = 0 
GROUP  BY prefixo 
ORDER  BY prefixo 

What am I doing wrong here?

Edit:

The expected result is the same that MySQL would give me with this query. It would exclude every duplicated value of the column PREFIXO. I want only 1 record of each value in the mentioned column.
The error message is this:

[Err] ORA-00979: not a GROUP BY expression

Answer 1

The GROUP BY is not useful outside of the context of an aggregate function like MIN() MAX() SUM() COUNT(), except perhaps to deduplicate rows. Just remove it. If you are looking to deduplicate results, use DISTINCT instead. If you use DISTINCT, it won’t be of much value unless you are more specific about the columns in the SELECT list, excluding the primary key column.

SELECT
  DISTINCT * 
FROM 
  AD_VOARNET_ATENDIMENTO_PISTA 
WHERE IS_CLOSED = 0
ORDER BY PREFIXO

GROUP BY is sometimes confused with ORDER BY. You already have an ORDER BY PREFIX0,