So in the super key, we can contain any attribute but one attribute data value should be different from the other.įor Example, In STUDENTS table have attributes – name could be same but roll no is always unique Super key is a superset of candidate key means super key contains candidate key attributes and also primary key attribute.Īctually super key is a supreme key, which may contain additional attributes that are not needed for unique identification. Super key is a key of one attribute or more than one attribute, which can be used to uniquely identify a row in a table. There are various types of keys in the DBMS. So we choose attributes (can be one or more attributes), which helps to identify any record in the database table. A key can be created by a combination of one or more columns in the database table.Īctually, in Database, we store data in the form of tables (called Relation), and in these tables, we store data row-wise (Entity wise) so to find a particular data (Row/Entity), we need something so we can easily find that data. When we create a database table, then we also create a DBMS key. It also allows establishing the relationship between tables. Why do we need a key in DBMS?Ī DBMS key is very important for database tables because it’s the only way that helps to identify a particular row (tuple) or group of rows in the database. A DBMS key is an attribute or a set of attributes, which is used to find a database record (row) in a database table.
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