UFN_SOCIALMEDIAACCOUNT_USERIDISVALID

create function dbo.UFN_SOCIALMEDIAACCOUNT_USERIDISVALID
(
    @SOCIALMEDIASERVICEID uniqueidentifier,
    @USERID nvarchar(100)
)
returns bit
as
begin
    declare @ISVALID bit = 0;

    select top 1
        @ISVALID =
            case
                when SOCIALMEDIASERVICE.ACCEPTSUSERNAME = 1 then
                    case when @USERID is null or @USERID = '' then 0 else 1 end
                else 1
            end
    from dbo.SOCIALMEDIASERVICE
    where ID = @SOCIALMEDIASERVICEID;

    return @ISVALID;
end