Types of Keys
A Key is a data item that exclusively identifies a record. In other words, key is a set of column(s) that is used to uniquely identify the record in a table. It is used to fetch or retrieve records / data-rows from data table according to the condition/requirement. Key provide several types of constraints like column can’t store duplicate values or null values. Keys are also used to generate relationship among different database tables or views. Types of Keys
Super Key
Minimal Super Key
Candidate Key
Primary Key
Unique Key
Alternate Key
Composite Key
Foreign Key
Natural Key
Surrogate Key
