What is referential integrity in Microsoft Access?

Posted on by Muna Meyer

What is referential integrity in Microsoft Access?

The purpose of referential integrity is to prevent orphan records – records that reference other records that no longer exist. You enforce referential integrity by enabling it for a table relationship. Once enforced, Access rejects any operation that would violate referential integrity for that table relationship.

How do you do referential integrity in Access?

Enforce Referential Integrity

  1. Click the Database Tools tab.
  2. Click the Relationships button.
  3. Click the Show Table button and add tables to the Relationships window.
  4. Click the related field in the first table and drag it to the related field in the second table.
  5. Check the Enforce Referential Integrity option.

What is declarative referential integrity?

Declarative Referential Integrity (DRI) ensures integrity of the database by a properly managed primary key and foreign key relationship. Correctly defined primary keys and foreign keys help query optimizer to select the best-suited execution plan for the query.

Which table types are used for referential integrity?

An introduction to foreign keys and referential integrity in…

  • Both tables must be of the InnoDB table type.
  • The fields used in the foreign key relationship must be indexed.
  • The fields used in the foreign key relationship must be similar in data type.

How do you create a relationship in Microsoft Access?

You do that by following these steps:

  1. Click the Database Tools tab on the Ribbon.
  2. From the Relationships group, click the Relationships button.
  3. For each pair of tables you want in the relationship, click the table and then click Add.
  4. After you finish adding tables, click the Close button.

What is the most common type of relationship between two tables?

A one-to-many relationship is the most common type of relationship. In a one-to-many relationship, a record in Table A can have many matching records in Table B, but a record in Table B has only one matching record in Table A.

What are the types of relationship in MS Access?

Relationships between Tables. There are three types of table relationships you can have in Access (One-to-Many, Many-to-Many, and One-to-one), however, the One-to-Many is the most useful for the beginner, so that is what we will look at, here.

What is Composite key give an example?

In a table representing students our primary key would now be firstName + lastName. Because students can have the same firstNames or the same lastNames these attributes are not simple keys. The primary key firstName + lastName for students is a composite key.