Monday, January 7, 2013

SQL Server Compact Code Snippet of the Week #1 : locate the ROWGUIDCOL column in a table

During the next many weeks, I plan to publish a short, weekly blog post with a (hopefully) useful code snippet relating to SQL Server Compact. The code snippets will come from 3 different areas: SQL Server Compact T-SQL statements, ADO.NET code and samples usage of my scripting API.

The ROWGUIDCOL column property is defined like this in Books Online:

Indicates that the new column is a row global unique identifier column. Only one uniqueidentifier column per table can be designated as the ROWGUIDCOL column. The ROWGUIDCOL property can be assigned only to a uniqueidentifier column.

ROWGUIDCOL automatically generates values for new rows inserted into the table.

(You can also use a default of NEWID() to automatically assign values to uniqueidentifier columns)

The ROWGUIDCOL is used by Merge Replication, all Merge Replicated tables must have a ROWGUIDCOL column.

Enough talk, show me the code snippet:

SELECT column_flags, column_name, table_name 
FROM information_schema.columns
WHERE column_flags = 378 OR column_flags = 282

I am using the undocumented “column_flags” column to determine the ROWGUIDCOL column, and the reason for the 2 different values is that a uniqueidentifier column can be either NULL or NOT NULL.

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