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