Simplify and correct following query

Question

How do I fix, and possibly simplify I guess, this SQL query, please?

SELECT * FROM table WHERE
   M IN (NULL,1) AND T IN (NULL,1) AND J IN (NULL,1) AND B IN (NULL,1)
   AND (ISNULL(M,0)+ISNULL(T,0)+ISNULL(J,0)+ISNULL(B,0))<4
   ORDER BY (ISNULL(M,0)+ISNULL(T,0)+ISNULL(J,0)+ISNULL(B,0)) DESC

table contains 4 columns (M,T,J,B) with 3 possibles values only NULL, 0, 1.

• First-line filters to get only entries containing NULL or 1.
• Second-line makes an addition to get the total of M+J+T+B and filters only if <4.
• Third-line ORDER BY the same Total, M+J+T+B.

error #1582 - Incorrect parameter count in the call to native function 'ISNULL'

MySQL equivalent to ISNULL is IFNULL... answered here

Answer 1

select * from (
    select *, coalesce(M,0) M2, coalesce(T,0) T2, coalesce(J,0) J2, coalesce(B,0) B2
    from table
    where 
     (M is null or M=1) and
     (T is null or T=1) and
     (J is null or J=1) and
     (B is null or B=1) 
)x
where M2+T2+J2+B2 < 4
order by M2+T2+J2+B2 desc