DATABASE

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Knowing your way around a database is a great marketable skill to have.

  1. A relational database is a collection of persistent data that's stored in multiple but related tables. A relationship is an association between two tables.

  2. The main database objects that you'll interact with are as follows :

    • A table stores the data.

    • A query asks a question about the data and returns the appropriate data in answer to the question.

    • A form lets you view and otherwise interact with the data.

    • A report groups and sorts data in meaningful ways.

  3. Alter an object's design in design view ; actually use the object in view mode.

  4. A table consists of rows and columns .

  5. A primary key is the field or fields that uniquely identify each record. A primary key value can't be null. To define a primary key, open the table in design view, right-click the appropriate field row, and select Primary Key from the resulting menu.

  6. An index is an internal structure that stores key values that act as pointers to the data.

  7. Referential integrity is a rule that protects the validity of your data as follows: A foreign key value must match a primary key value in a related table or be null. Specifically, you can't change a primary key value if a related record exists in another table. Or you can't enter a foreign key value before entering the same value as a primary key value in the related table. A foreign key is simply a primary key value in a related table.

  8. To relate two tables, open the Relationships window, add the two tables to the window, and then drag the primary key from one table to the matching field in the second table.

  9. Use field data types and properties to determine the type of data in a field and to control what the user enters and sees. The following are Access data types:

    Setting

    Smallest Value

    Largest Value

    Decimal Places

    Byte

    255

    Integer

    -32,768

    32,767

    Long Integer

    -2,147,483,648

    2,147,483,647

    Single

    -3.4 x 10 38

    3.4 x 10 38

    7

    Double

    -1.8 x 10 308

    1.8 x 10 308

    15

    Replication ID

    N/A

    N/A

    N/A

    Decimal

    -1.10 38

    1.10 38

    28


  10. There are a number of ways to sort and limit the data you see:

    • Apply a filter to a table or form using Filter by Selection or Filter by Form.

    • Sort data in a table or form by selecting a field and clicking Sort Ascending or Sort Descending.

    • Sort data in a query by specifying a sort order in the appropriate field's Sort control.

    • Limit the data returned by a query by choosing only those fields that you really need to view.

    • Limit the data returned by a query by adding a criteria expression in the Criteria control. Only those records that meet the conditions in the criteria expression will be returned by the query.

  11. Queries can be based on one or more tables; forms and reports can be based on tables or queries.

  12. To group report data, open the report in design view, click the Sorting and Group tool, and specify the fields by which you want to group the data and the sort order. If you use a wizard to create the report, the wizard might allow you to specify groups.

  13. Enter aggregate functions in a group's header or footer to summarize the data in each group. To display full-report summaries, add aggregate functions to the report's header or footer.

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ICDL Exam Cram 2
ICDL Exam Cram 2
ISBN: 0789730928
EAN: 2147483647
Year: 2006
Pages: 142

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