Query emulating ROW_NUMBER by session variable or derived table

Yii 2.0
1

I’d like to get a query to return a ROW_NUMBER; however, I’m using a version of MySQL old enough that it doesn’t have that as a built-in function. According to this page there are two ways to do it, using a session variable or a derived table:

SET @row_number = 0; 
SELECT 
    (@row_number:=@row_number + 1) AS num, 
    firstName, 
    lastName
FROM
    employees
ORDER BY firstName, lastName    
LIMIT 5;

SELECT 
    (@row_number:=@row_number + 1) AS num, 
    firstName, 
    lastName
FROM
    employees,
    (SELECT @row_number:=0) AS t
ORDER BY 
    firstName, 
    lastName    
LIMIT 5;

Unfortunately, I can’t seem to get Yii 2 to build the query this way. For the session variable, I don’t know how to get Yii 2 to prepend a line to the query. For the derived table, if I try to modify the from() field, it attempts to also add code to INNER JOIN the derived table.

2

Oh, never mind, I figured it out. The right way was to do:

$query->from(['(SELECT @row_number:=0) as t, employees']);

I was doing

$query->from(['(SELECT @row_number:=0) as t', 'employees']);