sql - Exclude matched array elements -

how can exclude matched elements of 1 array another?

postgres code:

a1 := '{1, 2, 5, 15}'::int[]; a2 := '{1, 2, 3, 6, 7, 9, 15}'::int[];  a3 := a2 ??magic_operator?? a1;

in a3 expect '{3, 6, 7, 9}'

final result

my , lad2025 solutions works fine.

solution array_position() required postgresql 9.5 , later, executes x3 faster.

the additional module intarray provides simple , fast subtraction operator - integer arrays, magic_operator looking for:

test=# select '{1, 2, 3, 6, 7, 9, 15}'::int[] - '{1, 2, 5, 15}'::int[] result;  ?column? -----------  {3,6,7,9}

you need install module once per database:

create extension intarray;

it provides special operator classes indexes:

... null-free arrays of integers.

Two