HPL/SQL examples

Greeting function🔗

The following example creates a function that takes the input of your name and returns "hello <name>":

CREATE PROCEDURE greet(name STRING)
BEGIN
  PRINT 'Hello ' || name;
END;

Pass a cursor to return records 🔗

This example of a procedure, called from another procedure, takes a cursor parameter declared OUT; an OPEN-FOR statement opens the cursor and executes the SELECT query. The query returns a subset of the records to the test_even procedure from the numbers table, created in a previous topic.

CREATE PROCEDURE even(cur OUT SYS_REFCURSOR)
BEGIN
OPEN cur FOR 
SELECT n FROM numbers 
WHERE MOD(n, 2) == 0;
END;  

The test_even procedure below calls the even procedure above, passing the cursor of type SYS_REFCURSOR to fetch each row containing an even number.

CREATE PROCEDURE test_even()
BEGIN
 DECLARE curs SYS_REFCURSOR;
 DECLARE n INT = 0;
 DECLARE result STRING = 'Even numbers are: ';
 even(curs);
 FETCH curs INTO n;
 WHILE (SQLCODE = 0) DO
    result = result || n || ' ';
    FETCH curs INTO n;
 END WHILE;
 CLOSE curs;
 PRINT result;
END;        

Using table types to index fields in records🔗

You can set up table types and reference fields in records using indexing. This example assumes you created the emp table.

-- CREATE TABLE emp (name string, age int);

TYPE emp_type IS TABLE OF emp%ROWTYPE INDEX BY BINARY_INTEGER;
TYPE emp_age_type IS TABLE OF emp.age%TYPE INDEX BY BINARY_INTEGER;
TYPE emp_name_type IS TABLE OF STRING INDEX BY BINARY_INTEGER;

DECLARE rows emp_type;
DECLARE ages emp_age_type;

SELECT * INTO rows(1) FROM emp WHERE name = 'alice';
PRINT 'name=' || rows(1).name || ' age=' || rows(1).age;

SELECT age INTO ages(1) FROM emp WHERE name = 'alice';
PRINT 'age=' || ages(1);   

BULK COLLECT🔗

Using BULK COLLECT, you can retrieve multiple rows in a single fetch quickly.

TYPE emp_type IS TABLE OF emp%ROWTYPE INDEX BY BINARY_INTEGER;
    DECLARE rows emp_type;
    
    SELECT * BULK COLLECT INTO rows FROM emp;
    
    
    DECLARE idx INT = rows.FIRST;
    WHILE idx IS NOT NULL LOOP
    PRINT rows(idx).name || ' = ' || rows(idx).age;
    idx = rows.NEXT(idx);
    END LOOP;