mysql 行号查询

1

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

2

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