PostgreSql how to declare variable type list

Question

In PostgreSql procedure, I need to create a list of integers to use in a delete statement, as in the example:

DELETE FROM appointment_virtual WHERE appointment_id IN (list_delete);

I need help with:

How do I declare a list type variable?
I found the following form, but I was unsure if it serves the purpose of the DELETE statement:

list_delete integer ARRAY;

How do I add items to this list variable?
I found the following way:

list_delete = array_append (_delete, _appointment_id);

How to zero the contents of this list variable?
Is the syntax below correct?

list_delete = [];

Thanks any help!

user_330315 · Answer

To define an array variable append [] to the end of the data type:

list_delete integer[];

To assign values use

list_delete := array[1,2];

to append an integer to the array:

list_delete := list_delete||4;

To assign an empty array use:

list_delete := CAST(array[] AS integer[]);

Or set it to null

list_delete := null;