SQL：表中选择数据库的最后一个ID

Question

I have the following query in my php script:

SELECT last_value FROM sys.identity_columns WHERE OBJECT_NAME(OBJECT_ID) = 'MYTABLE' AND last_value IS NOT NULL

This works great, it returns the last id from MYTABLE which is what I need.

But, as I'm going to have more than one database I should modify the query to select the database where MYTABLE is.

I'm doing:

SELECT last_value FROM sys.identity_columns WHERE OBJECT_NAME(OBJECT_ID) = 'mydatabase.dbo.MYTABLE' AND last_value IS NOT NULL

But this does not work, I get nothing in return.

Any ideas?

Thanks a lot!

Answer 1

When you execute an SQL statement, it runs in the context of a database you specified on connection. In order to query a different database you should change the database context. Try this:

USE MyDatabase;

SELECT last_value FROM sys.identity_columns WHERE OBJECT_NAME(OBJECT_ID) = 'MYTABLE' AND last_value IS NOT NULL

Answer 2

If you need to pass the database name as a variable IDENT_CURRENT accepts a database qualified object name. eg:

SELECT  IDENT_CURRENT('mydatabase.dbo.MYTABLE');

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As an unrelated aside it would be better to use:

WHERE OBJECT_ID = OBJECT_ID(N'MYTABLE');

Instead of

WHERE OBJECT_NAME(OBJECT_ID) = 'MYTABLE'

Since if MYTABLE was not in the default schema, it would fail, consider a table MYSCHEMA.MYTABLE. This returns no rows

WHERE OBJECT_NAME(OBJECT_ID) = 'MYSCHEMA.MYTABLE'

Whereas this would:

WHERE OBJECT_ID = OBJECT_ID(N'MYSCHEMA.MYTABLE');