Q130601: How to Create a Primary Index in a Visual FoxPro Program

Article: Q130601
Product(s): Microsoft FoxPro
Version(s): WINDOWS:3.0
Operating System(s): 
Keyword(s): kbcode
Last Modified: 11-FEB-2000

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The information in this article applies to:

- Microsoft Visual FoxPro for Windows, version 3.0 
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SUMMARY
=======

Microsoft Visual FoxPro has a new index type, Primary. The Primary index,
however, cannot be created in a program by using the INDEX command. This article
shows by example how to add or modify a Primary index in a program.

MORE INFORMATION
================

A Primary index is an index that never permits duplicate values on the specified
field or expression. The Primary index may be established in the database
container interface or in a program by using the CREATE TABLE or ALTER TABLE
command.

A table with a Primary index must be part of a database and cannot be a free
table. The first example shows how to create a table with a Primary index. The
second example shows how to alter an existing table to change a Primary key. The
third example adds a Primary index to an existing table.

Example 1 - Create a New Table with a Primary Index
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1. Create a new database, or open an existing one.

2. Issue the following command in the Command window to create a table with a
  Primary index on the cSsn key field:

     CREATE TABLE employee (cSsn C(11) PRIMARY KEY, cLast C(20),;
        cFirst C(20))

Example 2 - Modify an Existing Table to change a Primary Index
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1. Open the database used in example 1.

2. Issue the following command from the Command window to move the Primary index
  from the cSsn field to the cLast field:

     ALTER TABLE employee DROP PRIMARY KEY ADD PRIMARY KEY cLast TAG cLast

Example 3 - Modify an Existing Table to add a Primary Index
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1. Add a new table to an existing database with this command:

     CREATE TABLE noprime (cLast C(20))

2. From the Command window, add a Primary index to the existing table by using
  one of the following commands:

     ALTER TABLE noprime ADD PRIMARY KEY cLast TAG cLast

  -or-

     ALTER TABLE noprime ALTER COLUMN cLast C(20) PRIMARY KEY

Additional query words: VFoxWin

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Keywords          : kbcode 
Technology        : kbVFPsearch kbAudDeveloper kbVFP300
Version           : WINDOWS:3.0

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