Visual Basic.NET How to Program (PDF)

Chapter 21 ASP .NET and Web Services 1067
19
20 Friend WithEvents oleDbDeleteCommand1 As _
21 System.Data.OleDb.OleDbCommand
22
23 Friend WithEvents oleDbConnection1 As _
24 System.Data.OleDb.OleDbConnection
25
26 Friend WithEvents oleDbInsertCommand1 As _
27 System.Data.OleDb.OleDbCommand
28
29 Friend WithEvents oleDbSelectCommand1 As _
30 System.Data.OleDb.OleDbCommand
31
32 Friend WithEvents oleDbUpdateCommand1 As _
33 System.Data.OleDb.OleDbCommand
34
35 ' Visual Studio .NET generated code
36
37 ' checks database to determine if matching seat is available
38 _
39 Public Function Reserve(ByVal seatType As String, _
40 ByVal classType As String) As Boolean
41
42 ' try database connection
43 Try
44 Dim dataReader As OleDbDataReader
45
46 ' open database connection
47 oleDbConnection1.Open()
48
49 ' set and execute SQL query
50 oleDbDataAdapter1.SelectCommand.CommandText = _
51 "SELECT Number FROM Seats WHERE Type = '" & _
52 seatType & "' AND Class = '" & classType & _
53 "' AND Taken = '0'"
54 dataReader = _
55 oleDbDataAdapter1.SelectCommand.ExecuteReader()
56
57 ' if there were results, seat is available
58 If dataReader.Read() Then
59
60 Dim seatNumber As String = dataReader.GetString(0)
61 dataReader.Close()
62
63 ' update the first available seat to be taken
64 oleDbDataAdapter1.UpdateCommand.CommandText = _
65 "Update Seats Set Taken = '1' WHERE Number = '" _
66 & seatNumber & "'"
67
68 oleDbDataAdapter1.UpdateCommand.ExecuteNonQuery()
69
70 Return True
71 End If
Fig. 21.16 Airline reservation Web service (part 2 of 3).