Question

How can an index speed up the processing of a query whose WHERE clause contains the comparison "Salary = 50000"? What kind of index could help?

Answer 1

Database

Database Index is an object used to create and retrieve data from the database quickly and efficiently. There are 2 types of index, clustered index and non clustered index.

Clustered indexes store data physically in the table or view, Indexes with more than one column are called Clustered indexes.  whereas, non-clustered indexes do not store data in the table as it has separate structure from the data row.

CREATE INDEX index_name  ON table_name (column_name);

This is the syntax used for single column index, an index helps to speed up SELECT queries and WHERE clauses. In a database index will automatically retrieve the data from condition used in WHERE.

Select * FROM table_name where Salary =5000;