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Friday, April 28, 2006

Linked Server to Text Files - SQL2000

Sometimes it's handy to create a Linked Server to text files in order to perform distributed queries or bulk inserts of flat-file data into SQL Server.

In order to demonstrate this capability with SQL Server 2000, create a text file copy of the Categories table from Northwind database and place the text file named CATEGORIES.TXT in a subdirectory named TEXTFILES on a hard drive attached to the SQL Server machine.

Then add a Linked Server to the text file with a script like this:


exec sp_addlinkedserver NW_TEXT, 'Jet 4.0', 'Microsoft.Jet.OLEDB.4.0', 'Z:\TEXTFILES', NULL, 'Text'


Alternatively, you can add a Linked Server in Enterprise Manager:

Step 1
Linked Server Properties

 Step 2
New Linked Server dialog box 

 Step 3
Linked Server Properties - Security

Step 4
Linked Server - Server Options tab

This now allows you execute queries against the text file like this:


select
* from NW_TEXT...categories#txt



You can use a schema.ini file (Text File Driver) to provide formatting like column headers in a text file and make the file(s) browsable just like tables are when displaying them from the Linked Server node in Enterprise Manger.

For this example, create a schema.ini file that looks like this:


[CATEGORIES.TXT]
Format=CSVDelimited
CharacterSet=ANSI
ColNameHeaders=True
Col1=CategoryID Short
Col2=CategoryName Text Width 15
Col3=Description Text Width 100


For further information, check Schema.ini (Text File Driver) on Microsoft MSDN.

One caveate I ran across though, is that the maximum number of columns or fields that you can specify in a schema.ini file is 255. So, if you have a really W-I-D-E data file with lots of columns, and you are considering Linked Server with a schema.ini file, be aware of this limitation.

Hope this helps.
-pj

posted @ Friday, April 28, 2006 2:59 PM | Feedback (7) |

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