Because there is not a decent limit clause in MSSQL.

employee.sql

SELECT
                *
            FROM (
                SELECT
                    ROW_NUMBER() OVER (ORDER BY last_name asc) AS RowNum,
                    phppos_people.*,
                    phppos_employees.username,
                    phppos_employees.deleted
                FROM phppos_people
                    JOIN phppos_employees ON
                        phppos_people.person_id = phppos_employees.person_id
                WHERE
                    deleted = 0
            ) AS MyEmployees
            WHERE MyEmployees.RowNum BETWEEN 0 AND 20