Can't declare variable in Redshift UDF

Question

hi I'm unable to create this function, it throws me an error "syntax error near int". I'm using redshift

CREATE OR REPLACE FUNCTION stage.calc_enddate( int, int, timestamp)
    RETURNS timestamp
    LANGUAGE sql
    STABLE
AS $$
declare
 p int := 0;
begin 
    if ($1 >1) then
        select $3       
    end if
end
    
$$;

thanks in advance Sundar

Answer 1

According to Amazon Redshift's guide to the link

Data types

    CREATE OR REPLACE FUNCTION stage.calc_enddate(INT, INT, TIMESTAMP)
        RETURNS TIMESTAMP
    stable
    AS $$
    begin 
        if ($1 >1) then
            select $3       
        end if
    end
        
    $$ language sql;