Topics Software V:. Database concepts: records, fields, data types. Relational and objectoriented databases. Computer maintenance and operation: storage health and utilities; back-up strategies; keeping files and folders organized; virus checkers; etc. Database Essential Concepts Database collection of information stored in an organized way can consist of one or more files Database file (Table) made up of records Records organized into distinct fields Field separate area to store a certain type of information Database Table Files Record Fields What s s a Good Database System? Data integrity use data validation procedures Data independence: do not use proprietary data coding Avoidance of data redundancy Data security Data maintenance Using Database Software Finding information browse view list view queries Structured Query Language (SQL) Learn SQL online at Introduction to Structured Query Language, an online tutorial. Using Database Software Types of Database Programs Reports can be viewed on screen or printed Printing the data reports form letters report languages File management programs flat files (e.g. Excel documents) Database management systems (DBMS) relational database (Access) where tables are related by key fields object-oriented databases (elements in records are objects like whole files instead of pieces of information) Data warehousing & data mining Warehouse: primitive data from all depts. Mining: detection of patterns in data by statistical means 1
MS Access is a Relational Database Management System. Suppose you have a shop and you want to make some kind of database to store information about your products, your clients, and the orders they place... Flat database system: Create two tables: one with the information about your products and what is ordered and one with the information about your clients and their orders. The problem is that after some time, your tables will contain duplicate information; each order a client places needs to have his information repeated. Relational Database Management System: Put data about different types of entities in separate tables to avoid duplication and define relationships between the tables so that you still can get all the information. If you want to work relational then data must comply with the rules to be relational. Avoid redundant data Ensure referential integrity 1. What are the entities you want to describe? 2. How many kinds of entities do you have? 3. How will you describe them? 4. How will you identify them? People, products, Orders. 3 Name, address, Name, color, size, Who, what, when Key field Referential Integrity Rules that apply to the relationships between tables in a RDBMS. For example, take two related tables, A and B: What happens to the record(s) in table B if the record to which it is related, is deleted from table A? Or if one tries to add a record to table B that cannot be linked to table A? Or if you update the value of a linked field in table A, will the linked records from table B be modified accordingly? Relational Database Structure Access window elements Access button functions 2
Access objects: tab view Definition of Access objects Creating a Database Database data types Modifying Table: Design Fields, data types & descriptions 3
Editing Table Finding information in Table Results of FIND are not saved Using more complex Filters Removing Filters Queries can be saved 4
Using Forms to enter and display information Example of a Form Using Form Wizard Use Reports to create output Using the Report Wizard Example of a Report 5
Normalization 1. All data must be atomic. Each record has a UNIQUE ID. Eg: first and last names, address components 2. Blocks of data with repeated information that applies to several records should be broken up in to two or more additional tables, linked by means of a FOREIGN KEY. An attribute that completes a relationship with a parent entity. 3. Tables should only have columns that are fully dependent on the primary key. 6