1. PL/SQL Procedural Language / Structured Query Language

2. What is PL/SQL? PL/SQL is Oracle's extension to SQL with design features of programming languages. The data manipulation and query statements are included in the procedural units of codes. PL/SQL allows the applications to be written in a PL/SQL procedure or a package and stored within an Oracle server, where these PL/SQL codes can be used as shared libraries or applications, thus enhancing the integration and code reuse. Oracle pre-compiles PL/SQL codes prior to the actual code execution thus improving the performance.

3. See Handout: Chapter 2 What is PL/SQL? Client Side Server Side SQL ApplicationPL/SQL Application SQL Statement Processor PL/SQL Engine

4. PL/SQL Code Structure? DECLARE -- optional, which declares and define variables, cursors and user-defined exceptions. BEGIN -- mandatory - SQL statements - PL/SQL statements EXCEPTION -- optional, which specifies what actions to take when error occurs. END; -- mandatory

5. PL/SQL Example 1 -- Declare an Integer variable i.e. v1 -- Assign a value of 3 -- Print it on screen SET SERVEROUTPUT ON DECLARE v1 NUMBER(3); BEGIN v1 := 3; DBMS_OUTPUT.PUT_LINE('v1=' || v1); END;

6. PL/SQL Example 2 DECLARE TYPE v_arr IS VARRAY(25) of NUMBER(3); v1 v_arr; v_empno employee.empno%TYPE; BEGIN v1(2) := 3; DBMS_OUTPUT.PUT_LINE('The Value of v1(2) = ' || v1(2)); END;

7. DML Statements within PL/SQL DECLARE v_sal employee.sal%TYPE; BEGIN INSERT INTO employee VALUES (6, ‘John Smith', 10000); UPDATE employee SET sal = sal + 5000 WHERE empno = 6; SELECT sal INTO v_sal FROM employee WHERE empno = 6; DBMS_OUTPUT.PUT_LINE('Salary increased to ' || v_sal); COMMIT; END;

8. Control Statements Conditions Checking IF THEN [ELSIF THEN] [ELSE THEN] END IF;

9. Control Statements LOOP, FOR and WHILE Loops (1) LOOP... EXIT WHEN END LOOP; (2) FOR counter IN lower_bound.. upper_bound... END LOOP; (3) WHILE LOOP... END LOOP;

10. Cursor Manipulation See Handout: Chapter 8 DECLARE CURSOR csr_ac (p_name VARCHAR2) IS SELECT empno, name, sal FROM employee WHERE name LIKE '%p_name%'; v_a employee.empno%TYPE; v_b employee.name%TYPE; v_c employee.sal%TYPE; BEGIN OPEN csr_ac (‘Jo'); LOOP FETCH csr_ac INTO v_a, v_b, v_c; EXIT WHEN csr_ac%NOTFOUND; DBMS_OUTPUT.PUT_LINE(v_a || ' ' || v_b || ' '||v_c); END LOOP; CLOSE csr_ac; END;

11. Cursor Manipulation See Handout: Chapter 8 DECLARE CURSOR csr_ac (p_name VARCHAR2) IS SELECT empno, name, sal FROM employee WHERE name LIKE '%p_name%'; v_a employee.empno%TYPE; v_b employee.name%TYPE; v_c employee.sal%TYPE; BEGIN OPEN csr_ac (‘Jo'); LOOP FETCH csr_ac INTO v_a, v_b, v_c; EXIT WHEN csr_ac%NOTFOUND; DBMS_OUTPUT.PUT_LINE(v_a || ' ' || v_b || ' '||v_c); END LOOP; CLOSE csr_ac; END;

12. PL/SQL Procedures/Functions PL/SQL functions returns a scalar value and PL/SQL procedures return nothing. Both can take zero or more number of parameters as input or output. The special feature about PL/SQL is that a procedure/function argument can be of input (indicating the argument is read-only), output (indicating the argument is write-only) or both (both readable and writable). A function is called as part of an expression. For example, the function sal_ok might be called as follows: IF sal_ok(new_sal, new_title) THEN...

13. Procedures/Functions Examples PROCEDURE hire_employee (emp_id INTEGER, name VARCHAR2) IS BEGIN INSERT INTO employee VALUES (emp_id, name, 1000); END hire_employee; FUNCTION sal_ok (salary REAL, title REAL) RETURN BOOLEAN IS min_sal REAL; max_sal REAL; BEGIN SELECT losal, hisal INTO min_sal, max_sal FROM sals WHERE job = title; RETURN (salary >= min_sal) AND (salary <= max_sal); END sal_ok;