I was working on a spec for a new feature in our flagship application, when I wanted to included some simple database diagrams.  I was adding some new schema and I wanted to reference them in the spec.  I figured I would just do the schema changes in a spare database and make a database diagram.

I opened up MS SQL Server Management Studio (SSMS)) and connected to the database on a box running SQL Server 2000.  I selected the database and then selected “Database Diagram”.  SSMS got huffy about how the database diagrams in 2000 were nothing like the feature in 2005 and it wouldn’t touch it.  Gee thanks,  Microsoft.  The SQL Server team should have borrowed Raymond Chen for a while.  That wouldn’t have happened on his watch.

I connected to a SQL Server 2005 box and made my schema changes in a scrap database.  I selected database diagram and got a lovely error dialog with the following message:

Database diagram support objects cannot be installed because this database does not have a valid owner.  To continue, first use the Files page of the Database Properties dialog box or the ALTER AUTHORIZATION statement to set the database owner to a valid login, then add the database diagram support objects.

So I took the error message literally and took a peek at the owner.  I was the owner, and I have admin rights on that box. [Insert annoyed grunt here].  So I tried making sa to the owner, same error.  That obviously wasn’t the problem.

After a wee bit of googling, I came across the root cause of the error.  It was not an ownership issue, it was a database version issue.  We support both SQL Server 2000 and 2005, all of our databases are version 2000 compatible.  You can’t have 2005 database diagrams in a 2000 database, even it it’s attached to a 2005 server. 

There are a couple of ways to change the database, I opted for the T-SQL method:

EXEC

sp_dbcmptlevel ‘MyDataBase’, ’90’;

The sp_dbcmptlevel is documented here.  The value “90” corresponds to the version number of SQL Server 2005. I ran that command and I was able to add database diagram support to the database.  You can also make the change via SSMS with the following steps:

  1. Write click on database.
  2. Click on Properties.
  3. Click on Options.
  4. Change the Compatibility level to desired compatibility.
  5. Click OK.

After doing all of that, I really disliked the look of the tables in the database diagram.  It looked like the tabled editor from Access ’97.  So I ended up doing what I should have done in the first place, created a database diagram in Visio and copied that into my spec document.</p>

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