What is the use of creating indexes in table?

Question

What is the use of creating indexes in table? I need a simple explanation with example.... and also i need...if we create index means what it will do?

Senthilkumar · Answer

creating index on the table will improve the performance of the search query. Usually without index in the table is called table scan where it needs to scan row by row on all the columns. So it is costly to search and takes the time. But index is a mechanism to search in the index table it will find the appropriate matching records in the original table. It behaves like normal text book where it will have the contents in the front page and you can see the page number for quick navigation. There are two types of indexes. 1) Clustered index 2) Non clustered index Clustered index will create default when you have the unique key of the column. A table can have only one clustered index Non clustered will have the index table and a table can have many non clustered. CREATE INDEX IX_Product_Manfacturer ON Products(Manfacturer) when you search the manfacturer like this SELECT * FROM Products WHERE manfacturer='TVS' It will look into the index table. Hope this will help you.

Mahak Gupta · Answer

An Index is used to find the data quickly in the Table. A user can not see the Index. Syntax: create index index_name on table_name (column_name) For Ex: create index fn on Student(FirstName); It creates an Index(fn)for the FirstName Column of the Student Table. If we want to create an index on multiple columns in a table we write the following Code: create index fnln on Student(FirstNameLastName); We can also create a unique index like this: create unique index index_name on table_name (column_name)