Index Property

See Also    Example    Applies To

Sets or returns a value that indicates the name of the current CdbIndex object in a table-type CdbRecordset object (Microsoft Jet workspaces only).

Syntax

VOIDSetIndex(LPCTSTR pstr );

CStringGetIndex(VOID);

Parameters

Remarks

Records in base tables aren't stored in any particular order. Setting the Index property changes the order of records returned from the database; it doesn't affect the order in which the records are stored.

The specified CdbIndex object must already be defined. If you set the Index property to a CdbIndex object that doesn't exist or if the Index property isn't set when you use the Seek method, a trappable error occurs.

Examine the Indexes collection of a CdbTableDef object to determine what CdbIndex objects are available to table-type CdbRecordset objects created from that CdbTableDef object.

You can create a new index for the table by creating a new CdbIndex object, setting its properties, appending it to the Indexes collection of the underlying CdbTableDef object, and then reopening the CdbRecordset object.

Records returned from a table-type CdbRecordset object can be ordered only by the indexes defined for the underlying CdbTableDef object. To sort records in some other order, you can open a dynaset-, snapshot-, or forward-only–type CdbRecordset object by using an SQL statement with an ORDER BY clause.

Notes

• You don't have to create indexes for tables. With large, unindexed tables, accessing a specific record or creating a CdbRecordset object can take a long time. On the other hand, creating too many indexes slows down update, append, and delete operations because all indexes are automatically updated.
  
  
• Records read from tables without indexes are returned in no particular sequence.
  
  
• The Attributes property of each CdbField object in the CdbIndex object determines the order of records and consequently determines the access techniques to use for that index.
  
  
• A unique index helps optimize finding records.
  
  
• Indexes don't affect the physical order of a base table—indexes affect only how the records are accessed by the table-type CdbRecordset object when a particular index is chosen or when CdbRecordset is opened.