Data commit

Task/Ackermann-function/SQL-PL/ackermann-function.sql

@@ -0,0 +1,39 @@
+--#SET TERMINATOR @
+
+SET SERVEROUTPUT ON@
+
+CREATE OR REPLACE FUNCTION ACKERMANN(
+  IN M SMALLINT,
+  IN N BIGINT
+ ) RETURNS BIGINT
+ BEGIN
+  DECLARE RET BIGINT;
+  DECLARE STMT STATEMENT;
+
+  IF (M = 0) THEN
+   SET RET = N + 1;
+  ELSEIF (N = 0) THEN
+   PREPARE STMT FROM 'SET ? = ACKERMANN(? - 1, 1)';
+   EXECUTE STMT INTO RET USING M;
+  ELSE
+   PREPARE STMT FROM 'SET ? = ACKERMANN(? - 1, ACKERMANN(?, ? - 1))';
+   EXECUTE STMT INTO RET USING M, M, N;
+  END IF;
+  RETURN RET;
+ END @
+
+BEGIN
+ DECLARE M SMALLINT DEFAULT 0;
+ DECLARE N SMALLINT DEFAULT 0;
+ DECLARE MAX_LEVELS CONDITION FOR SQLSTATE '54038';
+ DECLARE CONTINUE HANDLER FOR MAX_LEVELS BEGIN END;
+
+ WHILE (N <= 6) DO
+  WHILE (M <= 3) DO
+   CALL DBMS_OUTPUT.PUT_LINE('ACKERMANN(' || M || ', ' || N || ') = ' || ACKERMANN(M, N));
+   SET M = M + 1;
+  END WHILE;
+  SET M = 0;
+  SET N = N + 1;
+ END WHILE;
+END @