Question

I have this in a stored proc in SQL Server:

      if not exists
        (my select statement)
            insert T
               (a, b, c)
            values
               (v_a, v_b, v_c)      -- arguments passed to the function


      select a,b,c from T where...;    -- return the row to the client after inserting it

Does postgreSQL have a counterpart to that if exists ( {select-statement} ) construct? The plpgsql compiler at first told me there was a missing “THEN” but when I corrected the if ... then syntax:

     create function foo(v_a int, v_b int, v_c int)
     returns TABLE (a int, b int, c int)
     as $body$
     begin
        if not exists
          (select id from T where ...) then
           insert into T
             (a, b, c)
           values
             (v_a, v_b, v_c);

       return QUERY
       select a,b,c from T where ...   ;

     end
     $body$
     LANGUAGE 'plpgsql'

the compilation terminates with:

       ERROR:  syntax error at end of input
       LINE 52: $body$ LANGUAGE 'plpgsql'
       .........^

so I’m assuming there’s some error upstream, but I don’t see it.

Answer 1

Your IF clause is incomplete. It must be closed by the corresponding END IF statement.

Check the docs on conditionals.