What is the candidate key?
As regards relational database management systems, the candidate key is an attribute that is used to identify the database series in the table. The system of relational databases is the type of database that is widely used to create collections of information organized on the basis of the provision of relations between different elements in the database table. The key is a tool that allows you to identify entities. Each table can have one or more candidate keys and one of these keys is set as the primary key. The primary key is a column that defines all rows. Superkey is the type of identifier that identifies the entity in the database table. SuperKey would be a column marked something as a vedn_code that would indicate a specific supplier code for a business database table. The minimum number of columns needed to make each row unique is part of a superkey that could be calculated as a candidate key. In this case, if each vend_code is unique, it can be a kanDidat's key.
In addition to being a candidate key, the supplier codes fields could also function as a primary key. Candidate keys work in conjunction with Superkeys and primary keys, and make sure the database does not have redundant lines, that is, each line has an element that makes it unique. When selecting the candidate key, it is important that the database creator chooses something that is unique for this table. As with the above example, a business database can be used as a candidate key. However, if it has several businesses, perhaps in different countries, the same name, this identifier would not be unique and could not be used as a candidate key.
Therefore, the choice of a unique candidate key is very important. Companies can share the same name; People often have the first and lasts that are the same or similar. By having a unique candidate key and making a poisonEN of them The primary key is easier to find a certain seller or person with a unique key. When each item has a key in the table that makes it unique, it is possible to distinguish between items that contain similar information.