Sunday, 15 October 2017

Getting information about referenced and referencing tables

At times we do need to carry out some tasks related to figure out certain information about references among some database objects. Today's post is going to show an example for tables by using T-SQL. There are two SQL Server system views we will use to query that information, they are 'sys.objects' and 'sys.sysreferences'. The view 'sys.objects' contains information for each database object (DDL and DML triggers) created inside of a particular user schema, and sys.sysreferences has the following important columns which will give us the object id of the referenced and referencing object.
  • rkeyid: Contains the ID of the object which is being referenced.
  • fkeyid: Contains the ID of the object which is referencing.  
For instance, now we are going to figure out which tables are being referenced from the 'Product' table inside the 'AdventureWorks' database:

SELECT S.[name] AS 'Referenced Table'
FROM sys.objects S INNER JOIN sys.sysreferences R 
   ON S.OBJECT_ID = R.rkeyid
WHERE S.[type] = 'U' AND R.fkeyid = OBJECT_ID('[Production].[Product]')

Having done that, we can also figure out which tables are referencing to the 'Product' table. 

SELECT S.[name] AS 'Referencing Table'
FROM sys.objects S INNER JOIN sys.sysreferences R 
   ON S.OBJECT_ID = R.fkeyid
WHERE S.[type] = 'U' AND R.fkeyid = OBJECT_ID('[Production].[Product]')

As I said earlier, not only can we use those views for tables, but also for other objects like functions, stored procedures, views, etc. I hope you can make the most out of this tip. Let me know any remarks you may have. Stay tuned.

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