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Saturday, 9 July 2016

Indexes Tutorial


     Index is a database object which is used to retrieve the data quickly from existing table. Indexes are classified into two types those are

Unique Index
     If we apply any primary key Constraint or unique Constraint or any particular column on the table oracle engine internally maintains one of the index mechanisms called UNIQUE Index.

Non Unique index
     An index mechanism which is performed by the user manually those indexes are can be called as non unique indexes. Whenever we apply an index mechanism on any particular column in the table then Oracle engine internally maintains a separate table called index table which maintains chain index relationship between the regular table and normal table.

Syntax to create an index
CREATE UNIQUE INDEX<Index name> AS TABLE NAME <Column name>
E.g
create unique index ix on ashok(no);

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     That's it guys. This is all about SQL Tutorial. Let me know your comments and suggestions about this tutorial. Thank you.

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