MySQL Select Statement, WHERE 'IN' Clause

Question

I currently have the following row in my table:

         course_data:
             user_id        days     <-- This is a varchar column.
               405          1,3,5

and I am trying to implement the following SELECT statement:

SELECT usrID, usrFirst, usrLast, usrEmail
    FROM tblUsers
    WHERE usrID NOT IN
    (
        SELECT users.usrID
            FROM
                `course_data` courses,
                `tblUsers` users
            WHERE
                days IN ('$day')
    )
    GROUP BY usrID
    ORDER BY usrID

Basically, I want that row (with user 405) to be omitted if the $day variable includes a '1, 3, or 5'.

For example, if $day = "1", it should return an empty query (because the number "1" is in the column "1,3,5").

However, I have not found this to be the case. Even though $day = "1", it still returns that row.

The only way that it won't return the row is if $day= "1,3,5." Yet, I thought that the IN() clause would take any part of my variable and apply it to that column.

Any insights on what I'm doing wrong here? Thanks.

Answer 1

Remove the Quotes in the IN Statement. The Syntax is:

... WHERE column IN (1,2,3) 

and not as you used it

... WHERE column IN ('1,2,3')

Also see the documentation on IN, there are more examples.