PostgreSQL/Postgre SQL/While

Simple While LOOP

postgres=#
postgres=# CREATE FUNCTION "count_by_two" (integer) RETURNS integer AS "
postgres"#      DECLARE
postgres"#           userNum ALIAS FOR $1;
postgres"#           i integer;
postgres"#      BEGIN
postgres"#           i := 1;
postgres"#           WHILE userNum < 20 LOOP
postgres"#                 i = i+1;
postgres"#                 return userNum;
postgres"#           END LOOP;
postgres"#
postgres"#      END;
postgres"#    " LANGUAGE "plpgsql";
CREATE FUNCTION
postgres=#
postgres=# select count_by_two(12);
 count_by_two
--------------
           12
(1 row)
postgres=#

Using the WHILE loop

postgres=#
postgres=#
postgres=# -- Using the WHILE loop
postgres=#
postgres=# CREATE FUNCTION add_two_loop (integer, integer) RETURNS integer AS "
postgres"#   DECLARE
postgres"#      -- Declare aliases for function arguments.
postgres"#     low_number ALIAS FOR $1;
postgres"#     high_number ALIAS FOR $2;
postgres"#
postgres"#      -- Declare a variable to hold the result.
postgres"#     result INTEGER = 0;
postgres"#
postgres"#   BEGIN
postgres"#      -- Add one to the variable result until the value of result is
postgres"#      -- equal to high_number.
postgres"#     WHILE result != high_number LOOP
postgres"#       result := result + 1;
postgres"#     END LOOP;
postgres"#
postgres"#     RETURN result;
postgres"#   END;
postgres"# " LANGUAGE "plpgsql";
ERROR:  function "add_two_loop" already exists with same argument types
postgres=#
postgres=# select add_two_loop(1,20);
 add_two_loop
--------------
           20
(1 row)
postgres=#