Creating Relationships in Microsoft Access 2007. Enforcing Referential Integrity. Extend Microsoft Access Applications to the Cloud. How Do I Use This Site? Ensuring Referential Integrity. Table relationships must obey standards of referential integrity, a set of rules that control how you can delete or modify data between related tables. Referential integrity in table. Referential Integrity in Microsoft SQL Server By Craig S. Mullins This article analyzes the various aspects that should be considered when implementing referential integrity. We may need to access it in its original. ![]() Referential integrity ensures that the. Today, even if your application uses SQL Server, that does not mean you must use. You might again choose to handle referential issues with application. Ensure data integrity with proper database design. Let's discuss how to use referential integrity to protect a database from incorrect and missing data. This article applies to a Microsoft Access database (.mdb or.accdb) file. SUMMARY., and that you do not accidentally delete or change related data. The following rules apply when you use referential integrity: You. Create, edit or delete a relationship. You change a relationship by selecting it in the Relationships window and then editing it. The Edit Relationships dialog box appears. Set the join type. When you define a table relationship, the facts about the relationship inform your query designs. For example, if you define a relationship between two tables, and you then create a query that employs the two tables, Access automatically selects the default matching fields based upon the fields specified in the relationship. You can override these initial default values in your query, but the values supplied by the relationship will often prove to be the correct ones. Because matching and bringing together data from more than one table is something you will do frequently in all but the most simple databases, setting defaults by creating relationships can be time saving and beneficial. A multiple table query combines information from more than one table by matching the values in common fields. The operation that does the matching and combining is called a join. For instance, suppose you want to display customer orders. You create a query that joins the Customers table and the Orders table on the Customer ID field. The query result contains customer information and order information for only those rows where a corresponding match was found. One of the values you can specify for each relationship is the join type. The join type tells Access which records to include in a query result. For example, consider again a query that joins the Customers table and the Orders table on the common fields that represents the Customer ID. Using the default join type (called an inner join), the query returns only the Customer rows and the Order rows where the common fields (also called the joined fields) are equal. However, suppose you want to include all Customers — even those who have not yet placed any orders. To accomplish this, you have to change the join type from an inner join to what is known as a left outer join. A left outer join returns all of the rows in the table on the left side of the relationship and only those that match in the table on the right. A right outer join returns all of the rows on the right and only those that match on the left. In this case, . Only include rows where the joined fields from both tables are equal. Inner join. Matching rows. Matching rows. 2. Include ALL records from 'Customers' and only those records from 'Orders' where the joined fields are equal. Left outer join. All rows. Matching rows. 3. Include ALL records from 'Orders' and only those records from 'Customers' where the joined fields are equal. Right outer join. Matching rows. All rows. When you choose option 2 or option 3, an arrow is shown on the relationship line. This arrow points to the side of the relationship that shows only matching rows.
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