Question

How can I declare int array in SQL Server?

After fill it, I would like to use it in IN statement to check, how can I change my code?

declare @mode int =1 
declare @acceptedFormTypeIds table (id int)

case @mode
    when 1 then
        insert into @acceptedFormTypeIds(id) values (1, 2, 3, 4)
    when 2 then 
        insert into @acceptedFormTypeIds(id) values (1, 3)
    when 3 then 
        insert into @acceptedFormTypeIds(id) values (2, 4)
    else
        insert into @acceptedFormTypeIds(id) values (1, 2, 3, 4)
end

...

WHERE
    tFRM.SendDate between @datefrom and @dateto
    and tFRM.TemplateId IN @acceptedFormTypeIds.id

Answer 1

In databases, don’t ever think of arrays. Think of sets, or tables.

The structure of the insert statement should be

insert into @acceptedFormTypeIds(id) values (1), (2), (3), (4)

You can use if

if @mode=2
begin
   insert into @acceptedFormTypeIds(id) values (1), (3)
end
else
begin
    if @mode=3
    begin
       insert into @acceptedFormTypeIds(id) values (2), (4)
    end
    else
    begin
       insert into @acceptedFormTypeIds(id) values (1), (2), (3), (4)
    end
end

However, it may be worth having a FormTypeModeAccepted table depending on your usage.