ADO.NET连接

Question

could someone explain me some of the main differences between Connection-oriented access and connectionless access in ADO.NET? And for what applications are they indended for? Thanks

Answer 1

Connection oriented model makes use of platform specific "data providers" such as OLEDB (namespace: System.Data.Oledb ), Microsoft SQL Server (namespace: System.Data.SqlClient ), ODBC (namespace: System.Data.Odbc ), etc.

When you are using these data providers your application assembly and database are tightly coupled using these data providers (that means connected every time).

Whereas in disconnected model we make you of DataSet, DataAdapter, etc. Here you can understand Dataset as a buffer and DataAdaptor as a bridge joining database and this dataset.

Once you make objects of DataAdapter(ad) and DataSet(ds) and write ad.Fill(ds) , this dataset gets its buffer (all the tables, etc.) from the database and now connection with database automatically breaks. All the future queries gets executed on this buffer (dataset) and then automatically, this updates your database after. In summary, your database is used only two times:

1. when dataset gets its buffer;
2. when updating the database takes place and rest all the time remains "Disconnected".

Answer 2

Connection Oriented means : connection is exist throw out your process. Example : using DataReader in Ado.Net you can get data as connection oriented database connection type. Connection Less means : Your connection is not available throw out your whole process. Example: using DataAdapter in Ado.Net you can get data as connection less database connection type.

Answer 3

In client-server model, each client creates its own database connection(con.open) at startup and releases(con.close) it when the program closes. Although the connection is only used for a fraction of time the client holds it open. Data Readers are used in this process. Data is read only in Connected Data Access Example - Phone call - we connect the call and disconnect the call Note - The server must maintain a separate, live connection for each client.

For Disconnected Data Access(Connection less) Data Adapters manage the connection internally to fetch the data from the database, once it fetches in closes automatically. so we wont write any con.open or con.close steps separately(manually). Data Adapters are used for this process. Example - Email Data can be manipulated such as insert, update.

Answer 4

Connection-Oriented As soon as you Open the connection using ConnectionObject.Open() the connection will always open until your close in manually using Close(). Components mainly used are:

1. Connection
2. Command
3. DataReader

Connection-less Data Adapter is used to Open and Close the connection. It ensures whether the data reached the dataset and the connection will be closed automatically. All your DML operation took place in dataset. If your perform any DML operation automatically Data Adapter opens the connection and update the data into the database and close the connection later on. Component mainly used are:

1. Connection
2. Data Adapter
3. DataSet

Answer 5

ADO.NET is framework for Database operation provided in .NET Framework.There are 2 sets of object

1)connection oriented - Those object that makes the DB connection like adaptor,connection,etc

2) connectionless -those object that stores data offline like Datatable,data colum, etc.They are very powerful not only u can store data but create relationship, query office , etc

When U make normal DB operation we use connection objects and use connectionless object to store the result set.

I suggest you read the documentation for more details.