Question 38: What are the Connection object properties and Connection class members?
Answer: The Connection class has a connection string that opens a connection to the database. The connection string will vary depending upon the provider used. The connection strings typically contain a group of property-value pair to describe how to connect to a database. For an OleDbConnection, you have properties such as Provider and DataSource.
| Property | Description |
| ConnectionString | Represent the connection string. |
| ConnectionTimeOut | Waiting time while establishing a connection. |
| DataBase | Name of the current database. |
| DataSource | Location of the file name of the data source. |
| Provider | Name of the OLE DB provider. This property is not available for Sql and ODBC data providers. |
| State | Current state of the connection of type ConnectionState. (Table 5-17 describes the ConnectionState). |
| PacketSize | Size of network packets. Available to only Sql data providers. |
| ServerVersion | SQL server version. Available to only Sql data providers. |
| WorkStationId | Database client ID. Available to only Sql data providers. |
The connection can have different states such as open, closed, connecting, and so on. The ConnectionType enumeration defines the members of the ConnectionState.
| Method | Description |
| BeginTransaction | Begins database transaction. |
| ChangeDatabase | Changes databases for an open connection. |
| Close | Closes an opened connection. |
| CreateCommand | Creates and return a Command object depends on the data providers. For example, OleDb Connection returns OleDbCommand, and SqlConnection returns SqlCommand. |
| Open | Open a new connection. |
| ReleaseObjectPool | Represents that the connection pooling can be cleared when the provider is released. Available only for Ole Db data providers. |
Question 27: Which namespaces are used for data access?
Answer: ADO.NET is a collection of managed libraries used by .NET applications for data source communication using a driver or provider.
ADO.NET provides libraries for the datasource communication under the following namespaces.
- Connection
- Command
- DataReader
- DataAdaptar
- CommandBuilder
- Parameter
See for more detail:
2 What is the difference between Dataset.clone and Dataset.copy?
Dataset.clone object copies structure of the dataset including schemas, relations and constraints. This will not copy data in the table.
Dataset.copy – Copies both structure and data from the table.
What are the main differences between ADO.NET and the classic ADO?
Following are the main differences between ADO and ADO.NET:
ADO |
ADO.NET |
|
ADO has a recordset |
ADO.NET has a data set and a data adapter. |
|
ADO objects interact in binary mode. |
ADO.NET uses XML for passing data. |
|
ADO mainly supports connection-oriented models. |
ADO.NET works in a discontinuous manner. |
|
ADO gains information about data at runtime. This information is based on metadata; thus, making it a costly process. |
ADO.NET uses identified metadata at design time; thus offering a better runtime performance and more efficient runtime behavior. |
|
Only client-side cursors are allowed. |
Supports both server-side and client-side cursors. |
