Why Do Relational Databases Use Primary Keys And Foreign Keys
Which of the following is correct in reference to a database.
Why do relational databases use primary keys and foreign keys. Tables are connected through primary and foreign keys to increase efficiency. Ill use a database I once made for an example and specifically three tables within that table. For implementation of 3NF rule Primary Key is one of the main aspect.
A primary key is a special relational database table column or combination of columns designated to uniquely identify each table record. Someone on this forum pointed to the MSDN videos on LEARNVISUALSTUDIONET which have been very helpful. For example if you delete a table or even a row in a table that other tables rely on the redundant data is removed.
It acts as a cross-reference between two tables as it references the primary key of another table. Also for joining any two tables in the relational database systems a Primary key and other tables Primary key is known as a Foreign Key which plays a vital role. Unfortunately while learning about relational databases and looking at the program that I want to design and make using them I have run into a pretty big wall concerning the primary key and foreign key.
Coincidentally PersonPhoneBusinessEntityID is not only a foreign key but is also part of PersonPhones primary key. A database can support many logical views. Primary keys and foreign keys are two types of constraints that can be used to enforce data integrity in SQL Server tables.
This topic contains the following sections. They help in terms of data normalization and data integrity. A foreign key is a column or group of columns in a relational database table that provides a link between data in two tables.
These are two different kinds of keys. A primary key is one or more columns in a table that are used to uniquely identify the row. What is information redundancy.
All tables in a relational database should not will just should have a declared primary key PK. A field or group of fields that uniquely identifies a given entity in a table. Why do relational databases use primary keys and foreign keys.
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