It is basically the same, you nee dfirst to GROUP By and then Makes the row_number
SET @row_number = 0;
SELECT
(@row_number:=@row_number + 1) AS num, firstName, lastName
FROM
(SELECT
firstName, lastName
FROM
employees
GROUP BY firstName , lastName) t1
ORDER BY firstName , lastName
With MySQL8.x this gets a lot easier.
I am not really sure what you mean by SELECT INTO
But i think you mean an outfile, as you have4 multiple values
SET @row_number = 0;
SELECT
(@row_number:=@row_number + 1) AS num, firstName, lastName
INTO OUTFILE '/tmp/result.txt' FIELDS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '"' LINES TERMINATED BY '\n'
FROM
(SELECT
firstName, lastName
FROM
employees
GROUP BY firstName , lastName) t1
ORDER BY firstName , lastName
If you want the selected data insert into another table thsi would look like
INSERT INTO table2
SELECT
(@row_number:=@row_number + 1) AS num, firstName, lastName
INTO OUTFILE '/tmp/result.txt' FIELDS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '"' LINES TERMINATED BY '\n'
FROM
(SELECT
firstName, lastName
FROM
employees
GROUP BY firstName , lastName) t1 , (SELECT @row_number = 0) t2
ORDER BY firstName , lastName