Query between two versions of the Database at runtime

One of my clients was using two versions of the same database and wanted a simple way to be able to check a condition in a query and switch between the two versions at runtime. Here’s a simple way to do it

Note: For demonstration purposes, I am pretending to check a condition in the form of the variable @Chk

DECLARE @Chk As Bit = 1

SET @Chk = 1

IF  @Chk = 1
    USE New_DB 
ELSE 
    USE Old_DB 
     
SELECT custid,custname FROM Customers

Now if @Chk = 1, then the query will be executed against the New_DB. Similarly if @Chk is not 1, the Old_DB will be selected.

About The Author

Suprotim Agarwal, MCSD, MCAD, MCDBA, MCSE, is the founder of DotNetCurry, DNC Magazine for Developers, SQLServerCurry and DevCurry. He has also authored a couple of books 51 Recipes using jQuery with ASP.NET Controls and a new one recently at The Absolutely Awesome jQuery CookBook.

Suprotim has received the prestigous Microsoft MVP award for nine times in a row now. In a professional capacity, he is the CEO of A2Z Knowledge Visuals Pvt Ltd, a digital group that represents premium web sites and digital publications comprising of Professional web, windows, mobile and cloud developers, technical managers, and architects.

Get in touch with him on Twitter @suprotimagarwal, LinkedIn or befriend him on Facebook