Identify the port that sql server is running on

Identify the port that SQL Server is running on:

DECLARE @tcp_port nvarchar(5)

EXEC xp_regread
@rootkey    =    ‘HKEY_LOCAL_MACHINE’,
@value_name    =    ‘TcpPort’,
@value        =    @tcp_port OUTPUT

select @tcp_port

Using XML parameters in SQL Server 2000 and above

The following is a minimal sample of extracting attribute based an element based data from an xml document in SQL Server.

declare @text varchar(1000)
set @text = ‘<a firstname=”Joe” surname=”Blogs” >42</a>’
DECLARE @idoc int
select @text

declare @name varchar(10)
declare @name2 varchar(10)

— Create an internal representation of the XML document.
EXEC sp_xml_preparedocument @idoc OUTPUT, @text
— Execute a SELECT statement using OPENXML rowset provider.
SELECT @name=surname, @name2 = [firstname]
FROM OPENXML (@idoc, ‘/a’,1)
      WITH ([firstname]  varchar(10),
            surname varchar(20))

select @name, @name2

SELECT age=[text]
FROM OPENXML (@idoc, ‘/a/text()’,2)

EXEC sp_xml_removedocument @idoc

Further schema comparison

The following is an extension of the previous post.

This is useful when dealing with sql server 2005 and custom schema’s.

(That is the prefix before database objects, not the structure of the database).

select, schemaName = SS.Name

from sysobjects SO

join sys.schemas SS ON SO.uid = SS.[schema_id]

where type = ‘U’

order by

Comparing Database Schema in SQL Server and Sybase

A common development problem is to keep the schema of two databases in step.

This lists the tables:

    select tableName=name from sysobjects where type = ‘U’ order by name

This lists the fields per table:

    select tableName =,
       colName =,
       colLength = sc.length,
       colOrder = sc.colid,
       dataType = 
  from sysobjects so
 inner join syscolumns sc on =
 inner join systypes st on st.usertype = sc.usertype
 where so.type = ‘U’
 order by, sc.colid
Between the two you have the tools needed to compare two database schemas.
The only restriction is the database access.

This does not compare contents – that is a different problem.

SQL Server Error handling problems part 2

SQL Server 2000 has even more error handling problems than I blogged about before.

It would appear that error handling has not been thought through at all.

Take the RAISERROR command as an example. This appears to be a very elegant means of raising errors to the user.  You only need to use sp_addmessage to register a new message. The problem is that the messages are server global.

This means that if you server is ever to host a third party application you cannot safely define your own messages for fear of a third party app stamping all over them.  This should be scoped at a database level, providing at least some control.

The more I look at sql server error handling the more depressed I get. 

Why you can't do without the transaction log…

I have been working with SQL Server 2000 for a while now.  I’m no DBA…

Today I encountered a problem that the investigation of which led me to a greater understanding of SQL Server.

We have a reasonably large database that is recreated everyday as a snapshot of a larger system. The transaction log was getting rather large. Given that the database is set up to use the Simple recovery model and we were using no explicit transactions why is it getting so large?

Why can’t we switch off the transaction log?

It turns out that it is almost impossible to write directly to the database – bulk inserts only.  A majority of data access goes directly into the transaction log  which is then applied to the database.   In order  to clear down the transaction  log you need to backup the transaction log or pretend that you have.

This can be performed with the command BACKUP LOG {database_name} NO_LOG.

Databases can be set up with the Auto-Shrink option (but it is not a good idea to do so).  This will allow the transaction log to shrink itself.  The problem is that you have no control over when this happens and it will kill performance when it occours – it will pick the worst possible time to do it.  The best option is to pick a known quiet time and backup the log yourself.

For more details see “Shrinking the Transaction Log” in Books Online.

In addition we found that all data modification commands are wrapped in an automatic transaction.  This meant that our transaction log included a 21 million row insert as a single transaction…

Error Handling in SQL 2000 is depressing

The whole buisness of error handling in sql server 2000 stored procedures is depressing.

For example if a query has an incorrect table structure then there is no way of handling that from within the sp.  

It is rather inconsistent, the best that can be acheived is a compromise. You have to check @@ERROR after every step.

I hope that SQL Server 2005  will be better once I am allowed to use it.

SQL Server Oddity and a fix.

Recently I found that @@SERVERNAME does not actually return the name of the server that the machine is running.

It returns the name that was last set using sp_addserver ‘NAME’, local

This makes a difference if you are  creating an image of a machine as a master copy.
All of the copied machines will think that they are the master machine.

The following script should detect and repair incorrect server names:





    PRINT ‘Server name differs’
            PRINT ‘Dropping server ‘ +  @OLDNAME          
            EXEC sp_dropserver @OLDNAME
            PRINT ‘Dropped server ‘ +  @OLDNAME          
        PRINT ‘Adding server ‘ + @NEWNAME
        EXEC sp_addserver @NEWNAME, ‘local’
        PRINT ‘Added server ‘ + @NEWNAME
        PRINT ‘Now stop and restart SQL Server’