A relationship works by matching data in key columns, usually columns with the same name in both tables. In most cases, the relationship matches the primary key from one table, which provides a unique identifier for each row, with an entry in the foreign key in the other table. For example, products can be associated with the specific category of products by creating a relationship between the CategoryID column in the Categories table (the primary key) and the CategoryID column in the Products table (the foreign key). | |
To create the relationship, you can drag and drop the CategoryID column in the Products table to the CategoryID column in the Categories table | |
Or you can select "New Relationship..." from the Query menu. | |
And select the columns you want. Join Types There are three join types, as follows: Option 1 defines an inner join. An inner join is a join where records from two tables are combined in a query's results only if values in the joined fields are equal. It is the most common join operation. Option 2 defines a left outer join. The result of this join contains all records of the Products table, even if the join-condition does not find any matching record in the Categories table. Option 3 defines a right outer join. The result of this join contains all records of the Categories table, even if the join-condition does not find any matching record in the Products table. | |
How to modify the type of join To modify the join type, right-click the "join" and select Properties | |
How to delete a relationship To delete a relationship, click the "join" to select it, and hit the DEL key |