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Maintaining A Database

Maintaining A Database. By: Dr. Ennis-Cole. 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. OBJECTIVES:.

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Maintaining A Database

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  1. Maintaining A Database By: Dr. Ennis-Cole Ennis-Cole, AC 2.01, CECS 5010.001

  2. 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 5010.001

  3. OBJECTIVES: • Change field properties • Copy a record from another Access database • Delete and change records Ennis-Cole, AC 2.01, CECS 5010.001

  4. 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 5010.001

  5. 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 5010.001

  6. 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 5010.001

  7. Field Size Settings for Numeric Fields: • Byte - stores whole numbers from 0-255 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 5010.001

  8. 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 5010.001

  9. 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 5010.001

  10. 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 5010.001

  11. 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 5010.001

  12. 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 5010.001

  13. 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. AC2.21-2.25 Ennis-Cole, AC 2.01, CECS 5010.001

  14. 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 5010.001

  15. 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 5010.001

  16. The Access RDBM Your Turn !!! Ennis-Cole, AC 2.01, CECS 5010.001

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