What is an index?

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What is an index?

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An index is a pointer to a table. It speeds up the process of data retrieval from a table. It is stored separately from a table for which it was created. Indexes can be created or dropped without affecting the data in a table. The syntax for creating an index is as follows:

CREATE INDEX <Index name>

Indexes can also be used for implementing data integrity in a table. A unique index does not allow duplicate values to enter in a row if a particular column is indexed as a unique index. The syntax for creating a unique index is as follows:

CREATE UNIQUE INDEX <Index name>


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