How does the access relationships window indicate the many field in a one
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Establishing Relationships in AccessYou use the Relationships window to establish relationships between Access tables, as shown in Figure 3.5. To open the Relationships window, click to select the Database Tools tab on the ribbon, and then select the Relationships tool in the Show/Hide group. If you have not established any relationships, the Show Table dialog box appears. The Show Table dialog box allows you to add tables to the Relationships window.
Figure 3.5 The Relationships window enables you to view, add, modify, and remove relationships between tables. Looking at the Relationships window, you can see the types of relationships that exist for each table. All the one-to-many and one-to-one relationships defined in a database are represented with a join line. If you enforce referential integrity between the tables involved in a one-to-many relationship, the join line between the tables appears with the number 1 on the one side of the relationship and with an infinity symbol (∞) on the many side of the relationship. One-to-one relationships appear with a 1 on both ends of the join lines. Establishing a Relationship Between Two TablesTo establish a relationship between two tables, follow these six steps:
Looking at Guidelines for Establishing RelationshipsYou must remember a few important points when establishing relationships. If you are not aware of these important gotchas, you could find yourself in some pretty hairy situations:
Create a new database and add a table called tblCustomers, another called tblOrders, and a third called tblOrderDetails. The tables should have the following fields: tblCustomers: CustomerID, CompanyName, Address, City, State, ZipCode tblOrders: OrderID, CustomerID, OrderDate, ShipVIA tblOrderDetails: OrderID, LineNumber, ItemID, Quantity, Price
Modifying an Existing RelationshipModifying an existing relationship is easy. Access gives you the capability to delete an existing relationship or to simply modify the nature of the relationship. To permanently remove a relationship between two tables, follow these three steps:
You often will want to modify the nature of a relationship rather than remove it. To modify a relationship, follow these four steps:
How are relationships indicated in the relationships window?In the Relationships window, the line joining two tables that visually indicates the common fields and the type of relationship. A format for displaying related records in a data sheet when you click the plus sign (+) next to a record in a table on the one side of a relationship.
What does a oneIn the relationship window in Access, the primary key side of a one-to-many relationship is denoted by a number 1. The foreign key side of a relationship is denoted by an infinity symbol.
How do you display the field list for all relationships in Access?On the Database Tools tab, in the Relationships group, click Relationships. On the Design tab, in the Relationships group, click All Relationships. All tables that have relationships are displayed, showing relationship lines.
How do you represent a manyTo create many-to-many relationships, you need to create a new table to connect the other two. This new table is called an intermediate table (or sometimes a linking or junction table).
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