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Microsoft Access 2003 Define some key Access terminology:. Field – A single characteristic or attribute of a person, place, object, event, or idea. Record – A set of related field values.
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Microsoft Access 2003 Define some key Access terminology: • Field – A single characteristic or attribute of a person, place, object, event, or idea. • Record – A set of related field values. • Table – A collection of records that can be identified as a category of data, such as Customers, Orders, or Inventory.
Relational database and keys • A relational database is a collection of tables that are related to one another based on common fields. • A field, or a collection of fields, is designated as the primary key of each table. • The primary key uniquely identifies a record in the table. • When the primary key of one table is represented in a second table to form a relationship, it is called a foreign key.
Learn how Access saves a database • The Save button in Access differs from the Save button in other Windows programs. • When you press the Save button in Access, you are saving the design of the Access objects and NOT the data itself. • Access saves data as it is entered • For this reason, the location at which you are storing your database must always be accessible while working with a particular database. • Save all changes and quit the Access program before copying or renaming your database (.accdb) file.
What is an Access query? • If you want to see just a portion of the data in a table (or tables) you can create a query. • A query is a question you ask about the data stored in a database table. • Access responds by displaying the data according to your question. • For example, if you ask to see all the customers from New York, the response would be to display only the records whose state field matches with NY
Query window in Design view • Allows you to specify the results you want for a query. • Can specify which fields you want to be included. • Can control what records are displayed in the query by specifying select query criteria. • Each column in the design grid represents a field that will be used in the query. • You can run the query at anytime to view the results according to the current specifications.
Selecting, displaying and sorting fields Drag or double-click fields to include. (Query result differs from a table's datasheet view in that only selected fields are displayed) The results of the query will be displayed in order by the primary key of the table unless you specify another sort order.
Update data using a query • You can use the query datasheet to update data in a table. • The query datasheet is a temporary view of the data. However, when you update data by means of the query datasheet, the updates are placed directly into the underlying table. • NOTE: You can only update fields that are in the query! • Primary Key? • To observe the actual changes made to the table, close the query and open the table in datasheet view.
Access is a relational database • A database is almost always a collection of tables. Access is a relational database management system that allows you to form relationships between the tables. • When you form a relationship between tables, you are joining the tables. • Tables are joined on common field(s) between the tables. • When tables are joined, you can view data from both tables as if the tables were one combined table.
Relationships • Tables can be joined in three ways; • one-to-one • one-to-many • many-to-many • A one-to-many relationship exists when a table has one record associated with a given value but the related table has many records for that value. • Table with one record is called the primary (parent) table • Table with many records is called the related (child) table • Queries can be defined to use the relationship to extract data from both tables in a single query.
Using referential integrity • When dealing with related tables, you need to decide if you want to enforce referential integrity. • Referential integrity allows you to maintain the integrity between related tables. • The rules associated with referential integrity specify that when you add a record to a related table, there must be a matching record in the primary table. • If you choose to enforce referential integrity, you can insure that you will not have orphaned records (records that have no matching record in the primary table).
Reports • You can create a report, which is a printable version of your data, formatted according to your specifications. • The data in the report can consist of data from a single table or multiple tables. • Access has a Reports Wizard that allows you to easily create a report. • The report can be based on a table or it can be based on a query.
Compacting a database • It is a good idea to periodically compact and repair a database to recover wasted space created by adding, deleting, and modifying records. • Access has a Compact and Repair feature: • Open a database • Click on the Office Button and then Manage • Select Compact and Repair Database.
