Connectiong and Retrieving in ADO.NET

Connectiong and Retrieving in ADO.NET

Connectiong and Retrieving in ADO.NET

1.Connecting to Data Sources

In ADO.NET you use a [connection] object to connect to a specific data source by supllying authentication information in a connection string.The [connection] object you used depends on the type of data source.There are following object:
    [OleDbConnection]
    [SqlConnection]
    [Odbcconnection]
    [OracleConnection]

(1)Establishing a Connection
1)Closing Connections
We recommend that you always close the connection after finished used it,so that the connection can be returned to the pool.The [using] block in C# auromatically disposes of the connection when the code exit the block,even in the case of an unhanldle exception.You can also use [close] or [dispose] methods of the connection object for the provider you are using.
2)Connecting to SQL Server
  // Assumes connectionString is a valid connection string.
  using (SqlConnection connection = new SqlConnection(connectionString))
  {
     connection.Open();
     // Do work here.
  }

参见上一个专题   Working with Connection Strings，其中访问ODBC,OLE DB,Oracle 的内容与其重复，这里不再赘述。