Indexes are a common way to enhance database performance. An index allows the database server to find and retrieve specific rows much faster than it could do without an index. But indexes also add overhead to the database system as a whole, so they should be used sensibly.
2 types of Indexes
A clustered index sorts and stores the data rows of the table or view in
order based on the clustered index key. The clustered index is
implemented as a B-tree index structure that supports fast retrieval of
the rows, based on their clustered index key values.
CREATE CLUSTERED INDEX MyIndex1 ON MyTable(Column1);
A nonclustered index can be defined on a table or view with a clustered
index or on a heap. Each index row in the nonclustered index contains the nonclustered key value and a row locator. This locator points to the data row in the clustered index or heap having the key value. The rows in the index are stored in the order of the index key values, but the data rows are not guaranteed to be in any particular order unless a clustered index is created on the table.
CREATE NONCLUSTERED INDEX MyIndex ON MyTable(Column1,Column2); Sabarimahesh, if this helps please login to Mark As Answer. | Alert Moderator