*This post may contain affiliate links. As an Amazon Associate we earn from qualifying purchases.
Databases form an integral part of most organizations as they help us?store, manipulate, organize, and access data. In a database interview, most interviewers ask about?how referential integrity works. Therefore, we have found the best way to help you answer this question as you aspire to begin your database management career.
All About Referential Integrity
Before diving into the nuts and bolts of?referential integrity, it?s only right that we explain what it entails. It is a data property that when met, every value of one column in a relation table will exist as a value of another column in another or the same relation table. Usually, the relational integrity can only work when the fields that are declared foreign keys can have either null values or those ones from the primary or candidate keys in the parent table.
Some of the techniques involved in referential integrity include cascading delete and cascading update. Through those two functions, changes that are effected to the linked table are shown in the primary table. For example, we can consider a school setup?which needs two tables titled Teachers and Students. The foreign key will contain an attribute referred to as TaughtBy. This attribute shows the record for the particular student?s teacher in the Teachers table.
In that case the referential integrity will dictate that:
- We only need to add a record?to the Students table if?the TaughtBy attribute shows to a solid record in the Teachers table.
- If the primary key for a column in the Teachers table changes, we have to modify all the corresponding columns in the Students table with the help of a cascading update.
- When we delete a record in the Teachers table, we must also deal with all the corresponding records in student table by?using the cascading delete. After enforcing the RI, Access blocks all the actions violating it.
The Functions of the Referential integrity
- It ascertains that users or applications do not input inconsistent data.
- It also ensures that there is no duplicate data, therefore it can reduce data redundancy.
- In one to many relationships, it eradicates ‘orphans’ and keeps the references in sync.
Therefore, it is important that you read about the different types of relationships, the primary key, and the foreign key.
Referential integrity has simplified the work when dealing with relational database management systems. Sorting out data without redundancies and inconsistency is vital for proper data management. Therefore, you should prepare adequately for this question before going to the interview room. Make sure to leave your thoughts and comments on this subject in the comments section.