SELECT
`users`.`employeeID` as `username`,
`users`.`firstName` as `fname`,
`users`.`lastName` as `lname`
FROM `enrollment`
INNER JOIN `users` ON `enrollment`.`employeeID` = `users`.`employeeID`
WHERE `enrollment`.`number` = [int]
AND
`enrollment`.`term` = [int]
AND
(
`enrollment`.`status` = 'E'
OR
`enrollment`.`status` = 'M'
)
ORDER BY
`users`.`lastName` ASC,
`users`.`firstName` ASC;

SELECT
`users`.`employeeID` as `username`,
`users`.`firstName` as `fname`,
`users`.`lastName` as `lname`
FROM `enrollment`
INNER JOIN
`users` ON `enrollment`.`employeeID` = `users`.`employeeID`
AND
`enrollment`.`number` = [int]
AND
`enrollment`.`term` = [int]
AND
(
`enrollment`.`status` = 'E'
OR
`enrollment`.`status` = 'M'
)
ORDER BY
`users`.`lastName` ASC,
`users`.`firstName` ASC;

id  select_type table   type    possible_keys   key key_len ref rows    Extra
1   SIMPLE  users   ALL PRIMARY NULL    NULL    NULL    52925   Using filesort
1   SIMPLE  enrollment  ref employeeID,number_term  employeeID  9   ezlrn.users.employeeID  2   Using where

SELECT
    `users`.`employeeID` as `username`,
    `users`.`firstName` as `fname`,
    `users`.`lastName` as `lname`
FROM `enrollment`
    INNER JOIN `users` ON `enrollment`.`employeeID` = `users`.`employeeID`
WHERE `enrollment`.`number` = [int]
    AND
    `enrollment`.`term` = [int]
    AND
    (
        `enrollment`.`status` = 'E'
    OR
    `enrollment`.`status` = 'M'
    )
    ORDER BY
        `users`.`lastName` ASC,
        `users`.`firstName` ASC;

-- CREATE INDEX enrollment_ndx ON enrollment(employeeID); -- wait on this one
CREATE INDEX users_ndx ON users(employeeID);

CREATE INDEX enrollment_ndx ON enrollment(employeeID, number, term, status);

CREATE INDEX idx1 ON enrollment (number, term, status);
CREATE INDEX idx2 ON users (employeeID); // if needed