How to show sequential number in MySQL query result

Question

I have some simple query:

SELECT foo, bar FROM table

i think you now whats the result looks like.

What I want to do is to show some

Answer 1

If somebody wants to display the row number after ordering records, something like this may work

set @a=0; 
select @a:=@a+1 serial_number,t.* 
from ( SELECT foo, bar FROM tableORDER BY bar ) t

Answer 2

select @rownum:=@rownum+1 No, foo, bar from table, (SELECT @rownum:=0) r;

Answer 3

The order gets scrambled if you are using GROUP BY clause in your query. The work around is putting your query inside the FROM clause like this.

SET @a:=0;
SELECT @a:=@a+1 No, output.*
FROM (
     SELECT foo, bar
     FROM table GROUP BY foo, bar
 ) output;

Answer 4

Neither of the answers worked for me, but based on bungdito's source, I realized you can do something easier:

SET @a:=0;
SELECT @a:=@a+1 No, foo, bar
FROM table;

So, first make sure SET @a:=0; runs. That will set up your variable, a. Then you can increment it in the results with @a:=@a+1. I tested this with GROUP BY, ORDER BY, even JOINS and it worked as expected.