1. PL/SQL Block Structure DECLARE - Optional Variables, cursors, user-defined exceptions BEGIN - Mandatory SQL Statements PL/SQL Statements EXCEPTIONS - Optional Actions to perform when errors occur END; - Mandatory

2. Block Types FUNCTION name RETURN datatype IS BEGIN --statements [EXCEPTION] END; PROCEDURE name IS BEGIN --statements [EXCEPTION] END; [DECLARE] BEGIN --statements [EXCEPTION] END; FunctionProcedureAnonymous

3. Handling Variables Declare and initialize variables in the declaration section. Assign new values to variables in the executable section. Pass values into PL/SQL blocks through parameters. View results through output variables.

4. Variable Declaration Two variables can have the same name, provided they are in different block. identifier [CONSTANT] datatype [NOT NULL] [:= | DEFAULT expr]; %TYPE Attribute – Declare a variable as a database table, column or previously declared variable.

5. Variable Declaration %ROWTYPE – Declare a variable according to a collection of columns in a database table – Example emp_recordemp%ROWTYPE; – Assigning value emp_record.emp_name = ‘DOUGLAS’;

6. Syntax Delimiters – +, -, *, /, =, @, ||, <>, !=, --, /*, */, :=, ; Identifiers – Can contain up to 30 characters. Literals – Must be enclosed in single quotation marks. Comments – Single-line comments: -- – Multi-line comments: /* … */

7. Nested Blocks and Variable Scope Statements can be nested wherever an executable statement is allowed. An exception section can contain nested blocks. Scope – A block can look up to the enclosing block. – A block cannot look down to enclosed blocks.

8. Programming Guidelines Code Convention – SQL Statements: Uppercase – PL/SQL Keywords: Uppercase – Datatypes: Uppercase – Identifiers and Parameters: Lowercase – Database Tables and Columns: Lowercase

9. Programming Guidelines Name Convention – Variable: v_name – Constant: c_name – Cursor: name_cursor – Exception: e_name – Table: name_table – Record: name_record – Parameter: p_name – Global Variable: g_name

10. Programming Guidelines Indenting – Indent each level of code DECLARE v_dept_noNUMBER(2); v_locationVARCHAR2(13); BEGIN SELECTdept_no, loc INTOv_dept_no v_location FROMdept WHEREd_name = ‘SALES’ END;

11. SQL Statements in PL/SQL SELECT – Can return on and only one row SELECT select_list INTO variable FROM table WHERE condition; – The variable can also be a record

12. SQL Statements in PL/SQL SELECT – Exceptions NO_DATA_FOUND TOO_MANY_ROWS – Example SELECT emp_id, name INTO v_emp_id, v_name FROM emp WHERE dept_name = ‘SALES’;

13. SQL Statements in PL/SQL INSERT INSERT INTO table (columns) VALUES (columns); – The order of the columns in the INSERT INTO statement must be the same as in the VALUES statement. – Example INSERT INTO emp (emp_no, emp_name) VALUES (emp_no_seq.NEXTVAL, ‘DOUGLAS’);

14. SQL Statements in PL/SQL UPDATE UPDATE table SET sal = sal + v_sal_increase WHERE job = ‘ANALYST’; – Can effect zero or more rows in a single statement.

15. SQL Statements in PL/SQL DELETE DELETE FROM table WHERE column = value; – Can effect zero or more rows in a single statement. – Example DELETE FROM emp WHERE emp_name = ‘DOUGLAS’;

16. Control Structures IF Statement IF Statements ELSIF Statements ELSE Statements END IF;

17. Basic Loop LOOP Statements; EXIT [WHEN condition] END LOOP; Example LOOP v_counter := v_counter + 1; EXIT WHEN v_counter > 10; END LOOP;

18. FOR Loop FOR counter in lower_bound.. upper_bound LOOP Statements; END LOOP; Example FOR i IN 1.. 10 LOOP v_counter := v_counter + 1; END LOOP;

19. WHILE Loop WHILE condition LOOP Statements; END LOOP; Example WHILE v_counter <= 10 LOOP v_counter := v_counter + 1; END LOOP;

20. PL/SQL Record TYPE type_name IS RECORD (field_declaration, field_declaration); identifier type_name; Example TYPE emp_record_type IS RECORD (emp_nameVARCHAR2(10), salNUMBER(7,2)); emp_recordemp_record_type;

21. Cursors Private work area Implicit – Used by the Oracle Server to parse and execute SQL statements. Explicit – Declared and named by the programmer. – Declared in the DECLARE section of the block structure.

22. Explicit Cursors Controlling Cursors – Declare Create a named SQL area – Open Identify the active set – Fetch Load the current row into variables – Empty Test for existing rows – Close Release the active set

23. Explicit Cursors Declaring the Cursor CURSOR cursor_name IS select_statement; – Do not include the INTO clause in the cursor declaration – ORDER BY clause can be used if necessary – Example CURSOR emp_cursor IS SELECT emp_no, emp_name FROM emp;

24. Explicit Cursors Opening the Cursor OPEN cursor_name; – executes the query and identify the active set – No rows, no exception – Always test if cursor is open before opening. IF NOT cursor_name%ISOPEN THEN OPEN cursor_name END IF;

25. Explicit Cursors Fetching Data from the Cursor – FETCH cursor_name INTO variables; A record can replace the variables. – Testing for rows IF cursor_name%NOTFOUND THEN Statements END IF;

26. Explicit Cursors Closing the Cursor – CLOSE cursor_name; – Test for a closed cursor IF cursor_name%ISOPEN THEN CLOSE cursor_name; END IF;

27. Explicit Cursors Attributes – %ISOPEN Evaluates to TRUE if the cursor is open. – %NOTFOUND Evaluates to TRUE if the most recent fetch does not return a row. – %FOUND Evaluates to TRUE if the most recent retch does return a row. – %ROWCOUND Evaluates to the total number of records returned so far.

28. Explicit Cursors Cursor FOR loops FOR record_name IN cursor_name LOOP Statements END LOOP; Example FOR emp_record IN emp_cursor LOOP Statements END LOOP; – Implicit open, fetch and close occur.

29. Explicit Cursors Parameters CURSOR cursor_name (parameter_name datatype) IS select_statement; – Example CURSOR emp_cursor (p_dept_no NUMBER) IS select_statement; OPEN emp_cursor(10); FOR emp_record IN emp_cursor(10) LOOP

30. Explicit Cursors FOR UPDATE Clause SELECT … FROM FOR UPDATE [OF column_reference] [NOWAIT] Explicit locking lets you deny access for the duration of a transaction Locks the rows before the update or delete Last clause in a select statement Use only when necessary NOWAIT will check if rows have already been locked

31. Explicit Cursors WHERE CURRENT OF Clause WHERE CURRENT OF cursor; – Use cursors to update or delete the current row. – Include the FOR UPDATE clause in the cursor in the cursor query to lock the rows first – Use the WHERE CURRENT OF clause to reference the current row from an explicit cursor. – Example UPDATE emp SET sal = emp_record.sal *1.10 WHERE CURRENT OF sal_cursor;

32. Trapping Exceptions Performed in the EXCEPTION section of the Block Structure EXCEPTION WHEN exception1 [OR exception2] THEN Statements WHEN exception3 [OR exception4] THEN Statements WHEN OTHERS THEN Statements

33. Trapping Exceptions WHEN OTHERS is the last clause – Will trap unspecified exceptions – Only one WHEN OTHERS clause is allowed Only one handler is processed before leaving the block Exceptions can be defined in the DECLARE section and used in the EXCEPTION section

34. Predefined Exceptions There are many predefined exceptions – Examples NO_DATE_FOUND TOO_MANY_ROWS INVALID_CURSOR ZERO_DIVIDE DUP_VAL_ON_INDEX

35. Functions for Trapping Exceptions SQLCODE – Returns the numeric value for the error code. – Can be assigned to a NUMBER variable. SQLERRM – Returns the message associated with the error number. – Can be assigned to a VARCHAR2 variable.

36. PL/SQL DBMS_OUTPUT.PUT_LINE – Will display information to the screen. – Must SET SERVEROUTPUT ON in SQL*Plus window. Other DBMS_OUTPUT procedures – Check the manual Slash (/) – PL/SQL block is terminated by a slash on a line by itself. – Used when creating blocks in SQL*Plus.

37. PL/SQL COMMIT – Will save all changes to the database permanently. ROLLBACK – Will remove all changes from the database back to the last COMMIT. DDL (Data Definition Language) – Cannot be used in a PL/SQL block – Example CREAT TABLE DROP TABLE

38. PL/SQL IS NULL – Checks if a value is null.