Access Lecture 1 Database Overview and Creating Tables Create an Employee Table

Why database for 110A Because businesses generate a lot of data What are some ways in which businesses use data they collect? Data is needed to generate meaningful information The bottom layer of a three tiered app You’ll be more prepared for BUS111 So it is important to have working knowledge of databases.

Overview of Access What is a database and how is it different from database management system? –A collection of related tables. –MySJSU is a database which has tables all related to you. Your profile, your classes and schedule, and your grades. –Database Management System (DBMS) provides the means to store, maintain and gain access to the data.

Components of a Database Bits: 1 and 0 Bytes: 8 bits ( ) Field (aka column, attribute): Several Characters (e.g. Name) Record (aka row): Several Fields (e.g. your school record) Primary key: Unique identifier for the record (e.g. SSN) Table: Group of records e.g. (my class record). Database: Group of related tables

An example of data stored in a database table

Different DBMS available in market? Oracle, DB2, Microsoft Access, Microsoft SQL Server, Firebird, PostgreSQL, MySQL, SQLite, FileMaker and Sybase Adaptive Server Enterprise (From Wikipedia – Click on link to read more)OracleDB2Microsoft AccessMicrosoft SQL ServerFirebirdPostgreSQL MySQLSQLiteFileMakerSybase Adaptive Server Enterprise For this class we focus on MS Access (2007) and Microsoft SQL Server (express 2005 version)

Let’s look at one… This is a student database…Called Our_students_in_class_exercise

Steps in creating database Plan: Purpose of the database, its scope. Remember adding a bathroom after a house is build costs 10 times as much. Design: Build conceptual data models, report formats, data dictionary. Develop: Create tables, queries, reports Implement: Populate the database and test Review: Periodic checks to ensure compliance

Access Database Limitations 2 gigabytes in size Maximum of 32,768 objects 64 character maximum in an object name 14 character maximum for passwords Support up to 255 concurrent users

Access Table Limitations have up to 64 characters in each field name have up to 255 fields be one of 2048 concurrent open tables be up to 1 gigabyte have 32 indexes be sorted by up to 255 characters in one or more fields

Creating your own databases Say you are hired by a company to automate their employee payroll system. What are some of the fields that you can think of?

Creating your own databases Some potential fields –EmployeeID, –Hire Date –first name –last name –address phone number –birth date –Picture –pay scale –Hours worked You can get this information by analyzing the existing records of the company.

Creating your own database You may need several tables to create this database. Why? Creating several tables ensures easier access, faster processing, and removes redundancy You can join these tables with relationships using primary and foreign keys

Creating your own employee database New database  blank database  select location where file needs to be saved. Name the database as employee. Create a new table using design view. Explore other views for enhanced learning. Notice different types of data types and associated properties. The first field is employeeID. Right click to make it primary key.

Creating a table Add the remaining fields –Hire date : Date/time –Last/FirstName: Text –Street/City/State/Zip: Text (e.g. State 2chars) –Phone: Text –Birth Date: Text –Save the table as EmpMain

Populating Tables This means to add records You don’t need to save as access automatically updates the table. You can delete, modify, add records now. You can delete, modify, and add fields too. However before you do this, you have to take into account the data integrity issues. You can play around with format, custom properties, and other options to enhance the experience.

Let’s add some records Add 3 records, completing the following fields: –EmployeeID –HireDate –LastName –FirstName –Street/City/State/Zip –Phone –BirthDate

Relationships PRIMARY KEY: It is a field (or combination of fields) that makes each record in a table unique. Every table must have a primary key and each record must have a unique value as its primary key Tables and their relationships to each other are stored Tables are related in a one-to-many (or one-to-one) relationship A foreign key is required to establish the relationship – one table’s foreign key is another table’s primary key.

Primary Keys PRIMARY KEY: It is a field (or combination of fields) that makes each record in a table unique. Every table must have a primary key and each record must have a unique value as its primary key. Primary keys

Examples of Properties Properties of the CustomerID Field Properties of the Gender Field

Data Types DATA TYPE: Determines the type of data that can be entered and the operations that can be performed on that data Access recognizes the following data types: Number (can be used in calculations) Text (alphanumeric characters up to 255 per field) Memo (alphanumeric value of unlimited length) Date/Time AutoNumber (numeric value, automatically increases) Yes/No OLE Object Currency Hyperlink Data Type

Importing Data For your course project you’ll be importing data for your student table into your database. First click on the “External Data” Tab in Access Select the Excel as the file type that you’ll be getting the data from This starts a wizard

Importing Data There are 3 options…create a new table with the imported data, add the imported data to an existing table (this requires that the imported and existing data are similar), or link a table. Will do the first Browse to where the import file is and open Click open and OK

Importing Data You should be a preview of the data, Click Next Select the checkbox that says “first row contains column headings” and Next Now you can see the column headings as your field names and you can modify each fields datatype if you need to and Next Select the key if you wish

Importing Data Now name your table something helpful and your done. You can now go into the table in access and modify its design – you’ll probably need to…