ADO.NET doubt

Question

1) is The coding technique for ADO.NET in mobile web application and ASP.NET web application the same?? 2) Do you know any website or reference book that teaches us how to setup up SQL Server 2000 ( or any version) and then using it to do data access with ADO.NET for mobile web application (like insert, update, delete records in database). I am quite blurred with this now........ 3) although i do not go really deep yet, but i know that in ADO.NET, there is a class called DataSet with which you can populate data from original data source (such as MS Access) and then make changes to it without affecting the original data source. So if i also want to reflect the changes in the original data source, what methods should i refer to???? (actually i roughly know how to populate Dataset with data from original data source but i do not know the coding technique to also send the changes from dataset back to original data source)

p.jones · Answer

DataSet object is an in-memory database that can be populated from an external database. Once you have a DataSet you can pass it around to other programs so they each have their own copies. DataSets are comprised of DataTable objects and DataRelation objects. DataTable can be populated from a SQL query lodged with a DataAdapter object. The DataAdapter acts like a broker between a DataTable and its SQL equivalent (which may be an actual database table). As well as retrieving into DataTable the DataAdapter can update the database from the DataTable. DataRelation are objects that create parent-child relations between DataTables for referential integrity and for navigation. DataRows and DataColumns are a grid-like representation of a DataTable's contents similar to rows and columns in a relational database. Connection objects are used by DataAdapter's to actually talk to the database. You can have Command and Parameters objects for direct use but DataAdapters are generally ok for creating their own Command objects on the fly. When a DataRow is edited it is set with a flag to say it has been updated and what type (created modified deleted). You extract these and tell the DataAdapter to process them against the database. If you loan out a DataSet by allowing another program a copy of it that other program sends back the changes only in a transactional DataSet object those are processed locally against teh database and then integrated into the central DataSet. You can call soem kind of commit then on the central DataSet. Do NOT merge transactional dataset with original unless you are happy with the update of teh database. Sometimes you may have to refresh your central dataset from the database. ADO.NET does not restrict you to DataSets you can use Command and Connect objects by themselves and also DataReaders (the latter are like cursors in embedded SQL).