SQL CREATE INDEX Statement
The CREATE INDEX statement is used to create indexes in tables.
Indexes allow the database application to find data fast; without reading the whole table.
Indexes
An index can be created in a table to find data more quickly and efficiently.
The users cannot see the indexes, they are just used to speed up searches/queries.
Note: Updating a table with indexes takes more time than updating a table without (because the indexes also need an update).
So you should only create indexes on columns (and tables) that will be frequently searched against.
SQL CREATE INDEX Syntax
Creates an index on a table. Duplicate values are allowed:
CREATE INDEX index_name
ON table_name (column_name) |
SQL CREATE UNIQUE INDEX Syntax
Creates a unique index on a table. Duplicate values are not allowed:
CREATE UNIQUE INDEX index_name
ON table_name (column_name) |
Note: The syntax for creating indexes varies amongst different databases. Therefore: Check the syntax for creating indexes in your database.
CREATE INDEX Example
The SQL statement below creates an index named "PIndex" on the "LastName" column in the "Persons" table:
CREATE INDEX PIndex
ON Persons (LastName) |
If you want to create an index on a combination of columns, you can list the column names within the parentheses, separated by commas:
CREATE INDEX PIndex
ON Persons (LastName, FirstName) |
The Altova MissionKit, recent winner of the Jolt Product Excellence and Productivity Award for Best Development Environment,
is an integrated suite of tools ideal for:
- XML development
- Web & Web services development
- Data mapping & integration
- Rendering & publishing XML & database data
- XBRL validation, taxonomy editing, transformation & rendering
The MissionKit for XML Developers includes XMLSpy®, MapForce®, and StyleVision® plus 3 additional tools for less than the price of 2.
Try all 6 products free for 30 days!
Download a fully-functional free trial
|
|
|
| 
