What is a secondary key in SQL?
Also to know is, what is a secondary key in a database?
DEFINITION: A secondary key is made on a field that you would like to be indexed for faster searches. A table can have more than one secondary key. The main purpose of a database is to store and search for data. When databases become large, possibly with hundreds of thousands of records, they can take a while to search
Beside above, what is difference between primary and secondary key? 3 Answers. Primary Key: Is a single field chosen by the designer to uniquely identify a record in a table (relation), cannot be null (empty/unassigned). Secondary (or Alternative) Key: Is any field in the table that isn't selected to be any of the two types above.
People also ask, what is primary and secondary key in SQL?
Secondary Key is the key that has not been selected to be the primary key. However, it is considered a candidate key for the primary key. Therefore, a candidate key not selected as a primary key is called secondary key. Candidate key is an attribute or set of attributes that you can consider as a Primary key.
What is alternate key SQL?
An alternate key is a key associated with one or more columns whose values uniquely identify every row in the table, but which is not the primary key. For example, where the primary key for a table may be the employee id, the alternate key might combine the first, middle, and last names of the employee.