BUG: Invalid ALTER TABLE Command Works and Corrupts DBC (194515)

RESOLUTION

To avoid creating an invalid object through the ALTER TABLE command, be sure to include an expression in the Add Foreign Key statement.

To remove the invalid object reference in the database, follow the steps listed below:

Note the object number in the error below: it is Object #14.
Use the database as a table.
Delete the record for Object #14 (if that is the object number in the error)
Pack the database.

Fix Code For "Steps To Reproduce" Sample

      CLOSE DATABASE ALL
      USE testdb.DBC
      DELETE FOR objectid=14 &&Delete object #14's record
      PACK
      USE

MORE INFORMATION

The ALTER TABLE command allows the entry of an Add Foreign Key statement without specifying an expression. This causes an invalid entry in the database referencing a relationship that does not exist. This causes the VALIDATE DATABASE command to return the following error:

"Object #14 (Relation 'Relation 1'): Cannot find associated Index referenced by this object"

Steps to Reproduce Behavior

Run the following code in a program file:

      #DEFINE DBCNAME    'testdb'
      #DEFINE TABNAME    'testtab'
      #DEFINE TABCOUNT      2

      CLEAR
      CLOSE DATA ALL
      DELETE FILE testdb.DBC
      DELETE FILE testdb.dc?

      CREATE DATABASE DBCNAME

      FOR lni = 1 TO TABCOUNT
         DELETE FILE (TABNAME+ALLTR(STR(lni)))+'.dbf'
         DELETE FILE (TABNAME+ALLTR(STR(lni)))+'.cdx'
         CREATE TABLE (TABNAME+ALLTR(STR(lni))) (F1 C(10) NOT NULL ;
            PRIMARY KEY, ;
            F2 C(10) NOT NULL)
      ENDFOR

      * Gives invalid DBC because Foreign key expression is missing
      ALTER TABLE (TABNAME+("2")) ADD FOREIGN KEY TAG ;
         F2 REFERENCES (TABNAME+"1") TAG F1

Issue the "VALIDATE DATABASE" command from the Command window. Note that this command returns the following error:
"Object #14 (Relation 'Relation 1'): Cannot find associated Index referenced by this object"

REFERENCES

For more information about the Alter Table command, search for "ALTER TABLE" in the Visual FoxPro Help file.

For additional information, please see the following articles in the Microsoft Knowledge Base:

186242 BUG: ALTER TABLE Cannot Create a Descending Primary Key

191697 BUG: ALTER TABLE Command With Multiple Drop Statements Fails

191593 BUG: ALTER TABLE Causes Memo File is Missing or Invalid Err