What is a junction table and how is it used in Microsoft Access?
A junction record is one which allows many to many relationship between the two owner records. One of the scenario in which junction table plays a role in Microsoft Access is while creating or defining many to many relationship. Many to Many relationships between two entities are one in which one row or record of a table can relate to many records in other table and also vice-versa for the other table. For instance consider a table named as exforsys with primary key as e1 and another table named as sample with primary key as s1 and if one wishes to create many to many relationship between these two tables it is done in Microsoft Access by using junction table as mentioned below:
First the two tables namely exforsys and sample are created. Then another table named as junction is created as junction table. In this table named as junction the primary keys namely e1 and s1 as defined in exforsys and sample are created and then a one to many relationship is created between exforsys and junction table and between sample and junction table. Thus in the junction table the primary key defined acts as foreign keys and relate the tables to each other.