Abstract Data Types

1
Abstract Data Types

• PL/SQL for Method Description

2
Getting Started

• Change settings
• SET SERVEROUTPUT ON
• Specify CREATE TYPE AS OBJECT statement
• Statement is ended by
• Type / under SQLPLUS prompt to execute the
  statement

3
Getting Errors

• If you get
• WarningType created with compilation errors.
• Under SQLPlus prompt type in
• SQLgt Show errors
• All errors are displayed
• You may DROP type or recreate the type using
• CREATE OR REPLACE statement

4
Basic Symbols in PL/SQL
5
Basic Structure of Method Implementation

• IS
• Declaration
• BEGIN
• Executable code
• END
• END

6
Declaration

• Contains method private variables
• Each variable has a name and type
• It is possible to assign initial value
• result integer 0

7
Method Arguments

• Argument role
• IN argument the value must be specified when
  the method is called
• OUT argument returns the value
• IN OUT argument does both passes the value to
  the methods and returns the value
• Argument description
• Name Role Type

8
Conditional Logic

• IF condition (is true) THEN
• BEGIN
• END
• ELSE
• BEGIN
• END
• END IF

9
SELECT in PL/SQL

• Similar to SELECT in SQLJ
• Declare a variable var
• SELECT something INTO var
• FROM Table
• WHERE qualification

10
Loops

• The condition is checked at the beginning
• WHILE (Xlt10) LOOP
• XX1
• END LOOP
• Fixed number of iterations
• FOR i IN 1100 LOOP
• END LOOP