ADOX Columns and Keys

seems1 · #1 (**permalink**) 07-15-04, 09:29

Hi,

I am having some difficulty using ADOX to retreive information ABOUT a database. (Not FROM it).

I want to know how (or if) it is possible to determine whether a Column in the Columns collection of an ADOX Table object is a Key column.

I am running the following code:

Code:

for each column in tableObj.Columns
   if(column.RelatedColumn = "") then
      response.write(column.name & "<br/>")
   end if
next

The problem is that I get an error because I am trying to access the RelatedColumn property of non-Key columns.

The online MSDN documentation is very unclear on this issue, RelatedColumn IS listed as a property of Column, but with the proviso that is only "for key columns". However the rest of the documentation indicates that Keys and Columns are entirely seperate objects with their own collections inside Table objects.

What i am trying to do is populate a drop down list with the names of all Columns that are NOT keys, but how can I determine which ones these are?

All help greatly appreciated!

rokslide · #2 (**permalink**) 07-15-04, 19:12

I've never tried to use this before but I just had a look through MSDN. What you are doing would appear to be fine but from what you are saying I can understand what is happening....

This isn't an elegant solution but it may help...

Code:

on error resume next
for each column in tableObj.Columns
   if(column.RelatedColumn = "") then
      if err.number = 0 then response.write(column.name & "<br/>")
   end if
   if err.number <> 0 then err.clear
next
on error goto 0

I wonder if there is a way to go through the properties collection of the column and determine if one of the properties is RelatedColumn and only if it is to grab it.... something like...

Code:

for each column in tableObj.Columns
   for each property in column.properties
      if property.name = "RelatedColumn" then
         if(column.RelatedColumn = "") then response.write(column.name & "<br/>")
      end if
   end if
next

HTH

seems1 · #3 (**permalink**) 07-16-04, 05:53

That seems a good idea, should have thought of it myself, thanks.

Regarding checking properties, apparently the contents of the properties collection depends on the Data Provider, and although this appears to be documented for ADO, I could find nothing for ADOX about this.

Thanks for your help!

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