Archive for May, 2010

IsNull and Dates

Posted: May 10, 2010 in TSQL

The following code was written expecting the results to be -1,-1

DECLARE @x as datetime;
set @x = NULL;
SELECT IsNull(@x,-1) AS Col_1, IsNull(NULL,-1) AS Col_2;

The actual result was 1899-12-31 00:00:00.000,-1

Why did it happen?

The reason it does this is because dates can be given INT values where 0 = 1900-01-01

All other dates are relative to that so:
1 = 1900-01-02
-1 = 1899-12-31

SELECT IsNull(@x,-1) AS Col_1;
Is the same as set @x = -1;
Which is the same as
set @x = ‘1899-12-31 00:00:00.000’;

So it did assign the value -1 to the date which then translated to Dec 31st 1899


Nearly everything in the package can be configured.

The main items you will want to configure are the passwords in server connections along with the name of the server and possible the initial catalog (database).
To set up a configuration option right click the package main window and select package configurations.
The options available are to use an XML file, Registry Entry, Parent Package Variable or a SQL database.
In this example I have a database called dataimports which I am going to use. In dataimports I have created a schema for each batch of work I use. This means I can separate out all the SSIS logging and configuration and I can give users access through the schemas.

Once you select the SQL server option you will need to select a database connection to use and then a table. If you already have config tables the drop down box will list them – else you can create a new one. You will need to type in a configuration filter. This is a key word that will match up the configuration settings in the table with this package. The name should be easily identifiably like >> DataDownload.
When you click next you will see a list of configurable items. If this is a new package there will not be very many.

You should try to restrict the configured values to the ones really needed else you will make reading the configuration table difficult which can lead to errors.

A config file should be used to store secure data – like passwords. It should also be used to store values which will or could change. For example a package which emails a user upon completion could have the To field of the email task configured. This way if you need to change the recipient you can change the config table. If a server name is going to change as the package is deployed then store the server name in a config file. You shouldn’t store static or trivial data like the protection level of a database connection – this will probably never change; or the connection string to a database and then all the individual elements of the connection. If you are using Windows Authentication you may not need to store any connection data.

What it looks like in the table:

I have created a primary key on ConfigurationFeature and PackagePath – the table is created without any primary key.

Note for passwords the value stored in the config file will be *****. This is a place holder. You will need to change this value to the actual password and set security on the table to stop people reading it.

If you look in the SQL Agent error logs it should record the problem – Subsystem %s could not be loaded.

When this happens you need to run this script:

use msdb;
delete from msdb.dbo.syssubsystems;
exec msdb.dbo.sp_verify_subsystems 1;

Now restart the SQL Agent


Error Message in SSMS

TITLE: Microsoft SQL Server Management Studio


Cannot show requested dialog.


Cannot show requested dialog. (SqlMgmt)

There is no row at position 0. (System.Data)

Problem is to do with system table spt_values being deleted.

Run this script to repair – the location may be different on your server.
C:\Program Files\Microsoft SQL Server\MSSQL\MSSQL.1\install\u_tables.sql

Before a filegroup can be removed all files associated with it need to be deleted.

Before a file can be deleted all objects associated with it need to be removed.

Just removing a file not a filegroup

If you have multiple files on a filegroup and you just want to get rid of one you can run this command.

DBCC ShrinkFile(logical_file_name,EmptyFile);

This will move any objects in the file onto the other files in the filegroup. You can then delete the file.

ALTER DATABASE DatabaseName REMOVE FILE logical_file_name;

Removing a file and a filegroup

To do this you will have to make sure that here are no objects associated with the file group. This could be Tables etc, Indexes, or even Blob objects.

This bit of code will show you the objects on a file group.

SELECT o.[name], o.[type], i.[name], i.[index_id], f.[name]

FROM sys.indexes i

INNER JOIN sys.filegroups f

ON i.data_space_id = f.data_space_id

INNER JOIN sys.all_objects o

ON i.[object_id] = o.[object_id]

WHERE i.data_space_id = f.data_space_id

AND o.type = ‘U’ — User Created Tables

I got this from:

If there are objects you want to keep you will need to move them to another filegroup. To move a non-clustered index you will need to drop and recreate it on the new file group. To move a table you need to drop and recreate the clustered index.

Once the filegroup has no user objects empty you can run the same commands for removing a file as – shrinkfile and remove file.

Then you will need to run the code below to drop the filegroup:

DATABASE [databaseName] REMOVE FILEGROUP [Filegroupname];

Remember: you can not drop the Primary filegroup.