How to Determine What Relations Exist in a .DBC (129640)


The information in this article applies to:

  • Microsoft Visual FoxPro for Windows 3.0
This article was previously published under Q129640

SUMMARY

The ADBOBJECT() function will create an array containing a a list of all persistent relations defined in a database container (.DBC file). This information can be useful outside of the database container. For example, it can be useful when you want to set relationships automatically for use within a one-to-many report.

MORE INFORMATION

The ADBOBJECT() function requires two parameters:
  • The first is the name of the array to be created.
  • The second indicates the type of information requested from the function.
For example, the following code creates an array called laRelations: 
   OPEN DATABASE \vfp\samples\mainsamp\data\tastrade
   =ADBOBJECT(laRelations, "RELATION")
   DISPLAY MEMORY
The array contains five columns. Each relationship defined in the DBC will occupy one row in the array. The columns contain the following information: 
   Column   Contents
   --------------------------------------------------------------
   1        Name of the parent table
   2        Name of the child table
   3        Name of the parent index tag involved in the relation
   4        Name of the child index tag involved in the relation
   5        Information for the Relational Integrity Builder
Column 5 contains up to three letters, indicating Update, Delete, and Insert triggers respectively. Each letter code within the column will contain a "C" for Cascade, an "R" for Restrict, or an "I" for Ignore. For example, a value of "CRR" in column 5 would indicate that updates should be cascaded, deletes should be restricted, and inserts should be restricted.

REFERENCES

The GENDBC utility uses this technique to define relationships as well as obtain other information from the DBC. If you would like to view the source code for this utility, it is stored as VFP\TOOLS\GENDBC\GENDBC.PRG.
Modification Type:MajorLast Reviewed:2/12/2000
Keywords:KB129640
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