To Use a SPQuery for getting the desired List data, We use Sharepoint's SPQuery class.

Some Important Notes about Using SPQuery.

* Use the Column Names that were kept Orignally when the Colum was made for the first time.(Not the ones that you see on column header,they may be same as they were kept earlier or may be not).

For eg, If you created a column with name "BName" and you changed the name(rename) to "BusinessName" later. You will have to use" BName" in SPQuery for getting the BusinessName column data Not "BusinessName".

More on SPQuery:

http://msdn2.microsoft.com/en-us/library/microsoft.sharepoint.spquery.aspx