Transcript Access
Access Review Access • Access is a database application • A database is a collection of records and files organized for a particular purpose • Objects under DB window: tables, queries, forms, and reports • Normal and design views of each object • Tables store information in records and fields • Each record is a collection of information about one specific thing, records stored in rows • Fields are categories of specific information stored in columns Access • 3 parts of a table: – Name – Field specification – Primary key • Table in a design view has two panes: Field pane and Field Properties pane • A query is a question you ask about the data stored in your tables or request you make to perform an action on the data Access • Select query retrieves records from one or more tables using criteria that you specify • Action query makes changes in the DB to records that meet the criteria that you specify • Form is an object designed and used for data input and/or display, one record at a time • Report is an object designed and used for formatting, calculating, summarizing and printing selected data Establishing Table Relationships • Fields that contain common values relate two tables • Primary key: field that contain a unique values can be chosen to be primary key in a table • Foreign key is a field in the related table that matches a primary key in the primary table • The primary table is the table in which the link field is the primary key Types of Relationships • After you decide to relate tables in a DB, you define the kind of relationships you want to establish • A one-to-one relationship means that any record in the primary table can have one related records • A one-to-many relationship means that any record in the primary table can have more than one related record in the related table. For example, instructor can teach many classes, but each class is taught by only one instructor • A many-to-many relationship means each table can have many related records. For example, a student is enrolled in many classes and each class has many students Tables’ Schema in a Database • If we had a DB with these two tables in it, table’s schema would be: Class Class_ID Student_ID Instructor_name Grade Primary key: Class_ID Student Student_ID Last_name Middle_name Last_name Phone_number Primary key: Student_ID Entity Relationship Diagram Class Takes_these Student