It’s really very confusing to keep track of many relationships that might occur in a very large database. Relationship in MS Access terms can be defined as one table being used in multiple tables in a database having common fields in more than one table which can involve primary and foreign key. Through Relationship builder you can have the clear picture of how the relationships between the tables in a database are setup. A Primary key identifies each record in a table uniquely. A primary key cannot be null, must be unique and only one can be defined in one table. Primary key can be defined either at the time of creating the table by creating a Primary key index or by using Constraint clause in the table declaration. Constraint limits the values entered in a field. A foreign key is the field or fields in a table which references the primary key of a different table. The data’s of this field in both the tables will exactly be the same.
There are mainly three types of relationships:
One-to-One: In One-to-One relationship there will be one and only one record in the foreign table for every record in the primary table.
One-to-Many: In One-to-Many relationship there might be one or more than one related records in the foreign table for every record in the primary table.
Many-to-Many: In Many-to-Many relationship there will be many related records in the foreign table for every related record in the primary table and vice-versa.
Below are the steps to view Microsoft Access Relationships with the Relationship Builder:
Open Microsoft Access.
Close all open tables and then hit the F11 key so as to open the database window.
Figure out the Relationship icon in the toolbar/tools menu and then hit the Relationship button with which the Relationships window will open. And in the Relationship window you will see images representing the tables that are related, if you have any established Relationships or else the window will remain empty.
If incase no Relationships are established, it can be created by using the Show Table Box. You can have access to it by choosing Show Table Box in the Relationships menu or by clicking on the Show Table icon in the toolbar.