Ennis-Cole, AC 2.01, CECS Maintaining A Database By: Dr. Ennis-Cole

Ennis-Cole, AC 2.01, CECS OBJECTIVES:  Learn the guidelines for designing databases and Access tables  Create and Save a table  Define fields and specify the primary key  Add records to a table  Modify the structure of a table  Delete, move, and add fields

Ennis-Cole, AC 2.01, CECS OBJECTIVES:  Change field properties  Copy a record from another Access database  Delete and change records

Ennis-Cole, AC 2.01, CECS Guidelines for Designing Databases:  Identify all the fields needed to produce the required information  Group related fields into tables  Determine each table’s Primary key  Include a common field in related tables  Avoid data redundancy  Determine the properties of each field

Ennis-Cole, AC 2.01, CECS Naming Fields and Objects in Access Tables  Fields can be 64-characters long  Fields can contain letters, numbers, and special characters; the first letter must be capitalized  Fields cannot contain., !, ‘, “ ”,and []  A table or query name must be unique  Extremely long names should be avoided  Standard abbreviations should be used

Ennis-Cole, AC 2.01, CECS Data Types:  You must assign a data type for each field  It determines what field values you can enter for the field  The field size defines a field value’s maximum storage size for text, numbers, and AutoNumber fields  Refer to Fig 2-4

Ennis-Cole, AC 2.01, CECS Field Size Settings for Numeric Fields:  Byte - stores whole numbers from in one byte  Integer - stores whole numbers from -32,768 to 32,767 in two bytes  Long Integer(default) - stores whole numbers from -2,147,483,648 to 2,147,483,647 in four bytes  Single - stores positive and negative numbers to precisely 7 decimal places & uses 4 bytes

Ennis-Cole, AC 2.01, CECS Field Size Settings for Numeric Fields:  Double - stores positive and negative numbers to precisely 15 decimal places and uses 8 bytes  Replication ID - establishes a unique identifier for the replication of tables, records, and other objects, uses 16 bytes  Decimal: stores positive and negative numbers to precisely 28 decimal places and uses 12 bytes

Ennis-Cole, AC 2.01, CECS Creating a Table:  Consists of naming the fields and defining the field’s properties  Specify a primary key, save the table structure  Start Access, open an existing file  Click Look in list arrow, open the database  Click New and Design View, Click OK

Ennis-Cole, AC 2.01, CECS Defining a Field in a Table:  Select the table, click the Design Button  Type the field name  Select the data type  Type or select other field properties  Refer to Figs. 2-8 through 2-13 for details

Ennis-Cole, AC 2.01, CECS Specifying a Primary Key  In the table window in Design View, click the row selector for the field to be the primary key  If primary key consists of two or more fields, press and hold down the Ctrl key  Click the row selector for each field  Click the Primary Key Button

Ennis-Cole, AC 2.01, CECS Saving a Table Structure:  Click the Save button on the Table Design Toolbar  Type the name of the table in the Save As Dialog Box  Click OK  Refer to Figs.2-17 through 2-19 for information on adding records to a table

Ennis-Cole, AC 2.01, CECS Modifying the Structure of An Access Table:  Delete a Field  Move a Field  Add a Field  Change Field Properties  Change the Format Property  Reference pp. AC

Ennis-Cole, AC 2.01, CECS Copying Records from Another Access Table:  Open the database  Click the appropriate table name & click open  Click row selector, click copy button - All the records are copied to Clipboard  Click Close, Click Yes and the Close button  Click File, Table name, and click row selector  Click Paste button, Click Yes to paste all the records

Ennis-Cole, AC 2.01, CECS Updating a Database:  Click Delete record button on the Table Datasheet toolbar  Click Yes to Delete a record  The F2 key is a toggle to switch between navigation and editing modes:  In navigation mode, an entire field value is selected  In edit mode, you can insert or delete characters in a field value based on the location of the Insertion Point  Refer to Fig. 2-31

Ennis-Cole, AC 2.01, CECS The Access RDBM Your Turn !!!