Commercial RDBMSs Access and Oracle

Access DBMS Architchecture  Can be used as a standalone system on a single PC: -JET Engine -Microsoft Data Engine (MSDE)  Can be used as a multi-user system on a PC network -File/server solutions -Client/server solutions -Database replication solutions -Web based database solutions

Creating a Table in Access  Use Table Wizard  Use Datasheet -Access creates table from sample of data  Use Design View  Use CREATE TABLE statement in SQL View

Access Enterprise Constraints  Validation rules for fields  Validation rules for records -Records will not be written unless they are valid  Validation rules for forms using Visual Basic for Applications -Used to add validation rules to Forms

Forms and Reports in Access  Form is GUI for entering data -Use VBA for custom logic  Reports are for displaying data in a formatted manner.

Access Macros  Access uses event driven paradigm -Mouse / Keyboard Events -Focus Events -Data events  Data Events can be used as triggers

Oracle DBMS Architechture  Tablespaces -Group related logical structures  Schemas -Named collection of schema objects  Data Blocks -Smallest unit of storage

Oracle Tables and Relationships  Create table with SQL CREATE TABLE  Create table with Create Table Wizard -Equivalent to Access Design View  Specify relationships in FOREIGN KEY property of create table  Does not support ON UPDATE, CASCADE, SET DEFAULT, SET NULL -Can get around this by using triggers

Oracle Enterprise Constraints  Several ways to enforce  SQL, via CHECK and CONSTRAINT clause of CREATE TABLE  Stored procedures and functions  Triggers  Methods

PL/SQL  Oracle Procedural extension to SQL  Cursors allow data to be accessed one row at a time  PL/SQL block has three parts - Declare variables, constants, cursors (optional) - Execution block - Exception block (optional)

Oracle Stored Procedures  PL/SQL block that can take parameters and be invoked.  Specify direction of parameters with IN, OUT, IN OUT  Package is a collection of procedures, functions, variables, and SQL statements that are grouped together.

Oracle Triggers  Trigger is an action to take when some event occurs under a certain condition  Types of events INSERT, UPDATE, DELETE CREATE, ALTER, DROP  The action will only execute if the condition is satisfied when the event occurs.

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