Introduction to database systems

Terminology The term "database" refers to the collection of related records. It is just data! A database management system (DBMS) is a software package with computer programs that controls the creation, maintenance, and use of a database. The database data collection with DBMS is called a database system. Referring to the software as a database is incorrect but not uncommon.

But really what is a database? Databases are used in real life, most of you use them without realizing it WVU Directory – uses databases Facebook – uses databases Google – uses databases Every time you are asked to input data, you’re accessing a database

An example Lets look at the WVU Directory page. What you see is sometimes called a Form – it is nothing more than a friendly front end interface.

Wvu directory

Wvu directory Say we want to search for all students named John Smith When you hit search it will run a query that looks like this: SELECT * FROM Students WHERE (((Students.FirstName)="John") AND ((Students.LastName)="Smith"))

An example – isolating results WVU has a database somewhere that lists all students, when we do a search we search that database for all students who have a first name John AND a last name Smith. We could either get exactly one result, no results or multiple results.

Question This brings up the question, how do we differentiate between the John Smith that is a Math major and the John Smith that is a Education major in our database? One way could be to use email addresses, since we hope everyone has a “unique” email address. But, is there another “unique” identifier that separates one person from another?

Student ID FirstName LastName Major Email A123 John Smith Math jsmith@email.com B122 Jane Finance jsmith1@email.com In this example we can see why using LastName as a “unique” way to identify students maybe a bad idea. StudentID, FirstName, LastName, Major, Email are called Fields. Each entry is called a Record, a collection of records make up a Table. A collection of tables make up a database. The Field StudentID has a special name called Primary Key since it uniquely identifies each student, no two students can have the same StudentID.

What is Access? Is a relational database management system from Microsoft. Allows the user to create relationships between tables It comes together with Graphical User Interface (GUI). Access is NOT a database – it is a database management system. There are numerous other database management systems.

Access vs Excel When to use Access? When you need a relational database to store your data or you anticipate adding more tables. When you have a large amount of data Rely on external databases to derive and analyze the data you need Need to maintain constant connectivity to an external database Need to regroup data from different tables in a single place with complex queries Have many people working in the database and need strong options to update the data

Access vs Excel When to use Excel? Require a flat or ‘non relational’ view of your data Want to run calculations or statistical comparisons on your data Know your data set is manageable (no more than 15,000 rows) 12

Access or excel Depending on the type of data that you are managing and what you want to do with that data. If your goal is to maintain data integrity in a format that can be accessed by multiple users, Access is your best choice, whereas Excel is better suited for complex numerical data that you want to analyze in depth. If you store your data by using Access and analyze it by using Excel, you can gain the benefits of both programs.

The HOME Tab HOME Tab – the basic Access tab. Contains basic editing functions such as cut and paste along with most formatting actions. Views Clipboard Text Formatting Records Sort & Filter Find 14

The CREATE Tab CREATE Tab – Brings together all create operations in one area. Includes ability to create queries through the wizard or in Design view. Tables Queries Forms Reports 15

The EXTERNAL DATA Tab EXTERNAL DATA Tab – Contains all operations to facilitate collaborations and data exchange. Import & Link Export Collect Data 16

The DATABASE TOOLS Tab DATABASE TOOLS Tab – The area that contains the operational backbone of Access. Here you create and maintain relationships of the database. You also analyze the file performance and perform routine maintenance. Tools Relationships 17

Basic elements of a database Field – is a basic entry or a data element, such as the name or a book or the telephone number. A field that uniquely identifies a record is called a Primary Key. Record – is a complete set of all of the data (fields) pertaining to one person, place, etc Table – is a collection of records, every table contains the same fields in the same order Database – consists of one or more tables and the supporting objects used to get data from those tables. 18

objects Objects are the components that make a database function. Four most commonly used object types Tables Queries Forms Reports All these objects can be created and managed from Create tab.

Comparing Access to Excel A FIELD in Access is equivalent to a COLUMN NAME in Excel A RECORD in Access is equivalent to a ROW in Excel A TABLE in Access is equivalent to a WORKSHEET in Excel A DATABASE in Access is equivalent to a WORKBOOK in Excel