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DBCREATEINDEX()
Create an index file
------------------------------------------------------------------------------
Syntax
DBCREATEINDEX(<cIndexName>, <cKeyExpr>,
[<bKeyExpr>], [<lUnique>]) --> NIL
Arguments
<cIndexName> is a character value that specifies the file name of
the index file to be created.
<cKeyExpr> is a character value that expresses the index key
expression in textual form.
<bKeyExpr> is a code block that expresses the index key expression
in executable form.
<lUnique> is an optional logical value that specifies whether a
unique index is to be created. If <lUnique> is omitted, the current
global _SET_UNIQUE setting is used.
Returns
DBCREATEINDEX() always returns NIL.
Description
DBCREATEINDEX() creates an index for the database (.dbf) file associated
with the current work area. If the work area has active indexes, they
are closed. After the new index is created, it becomes the controlling
index for the work area and is positioned to the first logical record.
DBCREATEINDEX() performs the same function as the standard INDEX
command. For more information, refer to the INDEX command.
Notes
. Side effects: DBCREATEINDEX() is guaranteed to create an index
that, when made active, will impose the specified logical order on
the database. The key expression is not necessarily evaluated at any
particular time, by any particular means, or on any particular record
or series of records. If the key expression relies on information
external to the database file or work area, the effect is
unpredictable. If the key expression changes the state of the work
area (e.g., by moving to a different record or changing the contents
of a record), the effect is unpredictable.
. Evaluation context: When the key expression is evaluated, the
associated work area is automatically selected as the current work
area before the evaluation; the previously selected work area is
automatically restored afterward.
. Network environment: DBCREATEINDEX() creates the new index for
the exclusive use of the current process.
. Illegal expression: If <cKeyExpr> evaluates to an illegal
expression, the code block will always evaluate to end-of-file (EOF).
Examples
. This example creates an index file, Name, indexed on the Name
field:
USE Employees NEW
DBCREATEINDEX( "Name", "Name", { || Name })
Files Library is CLIPPER.LIB.
See Also:
DBCLEARIND()
DBREINDEX()
DBSETINDEX()
DBSETORDER()
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