bsp; William Thompson
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How does the application work?OleDbConnection Object
OleDbConnection myConnection = new OleDbConnection(
@"Data Source=ASA 8.0 Sample;Provider=ASAProv.80");
The OleDbConnection object must be initialized before you can use any other ADO.NET objects. It creates the connection between the application and the database provider. This object requires the provider, in this case ASAProv or ASAProv.80. Then, you have to pass the rest of the connection string, which could be contained in a data source. If the engine is already running, then you only need to pass the user id and password, as follows: uid=dba;pwd=sql ; The connection string would look similar to the following:
OleDbConnection myConnection = new OleDbConnection("Provider=ASAProv.80;uid=dba;pwd=sql");
If you need the application to start the engine when you run it without using a DSN, then the connection string would look similar to the following:
OleDbConnection myConnection = new OleDbConnection(
@"Provider=ASAProv.80;uid=dba;pwd=sql;dbf=c:\temp\dbfile.db");
The @ sign prefacing the connection string allows the backslash in the file name to work; otherwise, double backslashes are necessary to escape the backslash character inside a C# string.
Open Connection Object
myConnection.Open()
This method is required to open the connection between the .NET application and the provider. If this method fails, an exception is thrown.
'System.Data.OleDb.OleDbException' occurred in system.data.dll
Once the connection is opened successfully, you can issue a SQL statement. First, a command object must be created to perform database operations. Once the command object is created, the CommandText property must be set. Since you want to fetch the first name and last name of the customers, you pass the SQL statement to the CommandText property of the Command object.
DataReader
The DataReader object is used in this example to quickly get the result of a query. This is a read only object: you cannot update the data.
The following code displays the data:
while ( myDataReader.Read())
{
Console.WriteLine("\t{0}\t{1}",
myDataReader["fname"],myDataReader["lname"]);
}
The DataReader's read() method allows you to read one row at a time. It returns true as long as there is data to read; otherwise, it returns false.
myDataReader.Close(); myConnection.Close();
Finally, you close the DataReader and Connection objects
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