Q92359: INFO: Using the FoxPro LOOKUP() Function
Article: Q92359
Product(s): Microsoft FoxPro
Version(s): MS-DOS:2.0,2.5x,2.6x; WINDOWS:2.5x,2.6x,3.0,5.0,6.0
Operating System(s):
Keyword(s):
Last Modified: 30-DEC-1999
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The information in this article applies to:
- Microsoft Visual FoxPro for Windows, versions 3.0, 5.0, 6.0
- Microsoft FoxPro for MS-DOS, versions 2.0, 2.5x, 2.6x
- Microsoft FoxPro for Windows, versions 2.5x, 2.6x
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SUMMARY
=======
The LOOKUP() function searches a database for the first occurrence of a
specified expression. If FoxPro finds the expression, it moves the record
pointer to the record that corresponds to the expression and returns the
contents of the specified field in the record. If no matching record is found,
the function returns the NULL string and leaves the record pointer at the end of
the file.
The LOOKUP() function can be used either to search for a specific expression in a
database or to search for the first occurrence of a matching field in a second
database.
MORE INFORMATION
================
The syntax of the LOOKUP() function is as follows
LOOKUP(<field1>,<expr>,<field2>[,<expC>])
where:
<field1> is the field to return.
<expr> is the string to search for.
<field2> is the field to search.
<expC> is the compact index tag to use in the search (optional).
Examples
--------
The following code searches the CUSTOMER.DBF file for the first occurrence of
"Mark Cummings" in the CONTACT field. If LOOKUP() finds a matching record, it
returns the contents of the COMPANY field.
USE CUSTOMER
?LOOKUP(COMPANY,"Mark Cummings",CONTACT)
The following code uses both the CUSTOMER.DBF and INVOICES.DBF files. LOOKUP()
moves the record pointer through the CUSTOMER database until it finds a record
that matches the current CNO field in INVOICES. LOOKUP() returns the contents of
the COMPANY field in the CUSTOMER database.
SELECT A
USE INVOICES
SELECT B
USE CUSTOMER
?LOOKUP(COMPANY,INVOICES.CNO,CNO)
If LOOKUP() includes the name of a compact index tag in the optional character
expression <expC>, the search expression should match the index expression
for the compact index tag. You can search the database for the contents of one
field or a combination of fields by including the name of a compact index tag.
The following code adds the CONTACT tag to the first example above:
?LOOKUP(COMPANY,"Mark Cummings",CONTACT,"CONTACT")
When the LOOKUP() expression does not specify a tag and the database is indexed,
FoxPro searches the primary index for the expression. If no index is available,
the LOCATE command is used to search the database.
NOTE: The Rushmore query-optimization system cannot optimize a LOOKUP() call.
Additional query words: VFoxWin FoxDos FoxWin 2.50 2.50a 2.50b 2.60 2.60a lookup look up
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Keywords :
Technology : kbVFPsearch kbAudDeveloper kbFoxproSearch kbZNotKeyword3 kbFoxPro200DOS kbVFP300 kbVFP500 kbVFP600
Version : MS-DOS:2.0,2.5x,2.6x; WINDOWS:2.5x,2.6x,3.0,5.0,6.0
Issue type : kbinfo
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