KDB: How do I perform a minus on 2 Lists

Question

Input:

a: 1 2 3 4 5 
b: 5 2 6 7

What operation do I need to do to remove all elements of b in a?

Expected Output:

1 3 4

Answer 1

I think the keyword you are looking for is except, like so:

q)c: a except b
q)c
    1 3 4

Except returns all elements of its left argument that are absent from the right argument.