class1.vb

这是一个完善的图书馆管理系统.后台数据库采用ACCESS.

    Public Function SelectQuery(ByVal SelectString As String, ByRef SelectData As Object) As Boolean
        Dim ret As Boolean = True
        Try
            If Connection.State = ConnectionState.Closed Then
                Connection.Open()
            End If
            Command.CommandText = SelectString
            Command.CommandType = CommandType.Text
            Adapter.SelectCommand = Command
            Adapter.Fill(SelectData)
        Catch ex As Exception
            ret = False
            DisplayError(ex)
        Finally
            Connection.Close()
        End Try
        SelectQuery = ret
    End Function

    '连接到DB2数据库
    'Server ---- 服务器地址或名称
    'DbName ----- 要连接到的数据库名称
    'UserId ---- 用户名
    'Password ---- 登录口令
    Public Function Db2Connection(ByVal Server As String, ByVal DbName As String, ByVal UserId As String, ByVal Password As String) As Boolean
        Dim ret As Boolean = True
        '如果数据库连接没有打开，尝试打开数据库连接
        If Connection.State = ConnectionState.Closed Then
            '构造连接字串
            ConnString = "Provider=IBMDADB2.1;Mode=ReadWrite;UID=" & _
                          UserId & ";PWD=" & Password & ";Data Source=" & DbName & _
                         ";Location=" & Server
            Try
                Connection.ConnectionString = ConnString
                Connection.Open()
            Catch ex As Exception
                ret = False
                DisplayError(ex)
            End Try
        End If
        Db2Connection = ret '返回函数结果
    End Function

    '关闭数据库连接
    Public Function CloseConnection()
        If Connection.State = ConnectionState.Open Then
            Try
                Connection.Close() '关闭数据库连接
            Catch ex As Exception
                DisplayError(ex)
            End Try
        End If
    End Function

    '接口CreateConnection ----- 创建数据库连接,自定义连接字串，可连接各种数据库
    'connString ----- 连接字串
    '成功返回 True，否则返回 False
    Public Function CreateConnection(ByVal ConnectionString As String) As Boolean
        Dim ret As Boolean = True
        ConnString = ConnectionString
        '如果数据库连接没有打开，尝试打开数据库连接
        If Connection.State = ConnectionState.Closed Then
            Try
                Connection.ConnectionString = ConnectionString
                Connection.Open()
            Catch ex As Exception
                ret = False
                DisplayError(ex)
            End Try
        End If
        CreateConnection = ret '返回函数结果
    End Function

    '接口AccessConnection ----- 连接到Access数据库
    'DbPath ---- 数据库完整路径
    'UserId ---- 用户名
    'Passord ----- 用户密码
    '成功返回 True，否则返回 False
    Public Function AccessConnection(ByVal DbPath As String, ByVal UserId As String, ByVal Password As String) As Boolean
        Dim ret As Boolean = True
        '如果数据库连接没有打开，尝试打开数据库连接
        If Connection.State = ConnectionState.Closed Then
            '构造连接字串
            ConnString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & _
                          DbPath & ";User Id=" & UserId & ";Password=" & Password & ";"
            Try
                Connection.ConnectionString = ConnString
                Connection.Open()
            Catch ex As Exception
                ret = False
                DisplayError(ex)
            End Try
        End If
        AccessConnection = ret '返回函数结果
    End Function

    '接口SqlConnection ----- 连接到SQL Server数据库(通过用户名和密码登录）
    'DbName ---- 数据库名
    'UserId ---- 用户名
    'Passord ----- 用户密码
    'DataSource ----- 要连接的SQL实例的名字或者网络地址
    '如果是网络地址，IP地址后要加个端口号，如:190.190.200.100,1433,SQL缺省的端口号为1433
    '成功返回 True，否则返回 False
    Public Function SqlConnection(ByVal DataSource As String, ByVal DbName As String, ByVal UserId As String, ByVal Password As String) As Boolean

        Dim ret As Boolean = True
        '如果数据库连接没有打开，尝试打开数据库连接
        If Connection.State = ConnectionState.Closed Then
            '构造连接字串
            ConnString = "Provider=SQLOLEDB.1;Initial Catalog=" & _
                          DbName & ";Data Source=" & DataSource & ";User Id=" & UserId & _
                          ";Password=" & Password & ";"
            Try
                Connection.ConnectionString = ConnString
                Connection.Open()
            Catch ex As Exception
                ret = False
                DisplayError(ex)
            End Try
        End If
        SqlConnection = ret '返回函数结果
    End Function

    '接口SqlConnection ----- 连接到SQL Server数据库(信任安全连接）
    'DbName ---- 数据库名
    'DataSource ----- 要连接的SQL实例的名字
    '成功返回 True，否则返回 False
    Public Function SqlConnection(ByVal DataSource As String, ByVal DbName As String) As Boolean
        Dim ret As Boolean = True
        '如果数据库连接没有打开，尝试打开数据库连接
        If Connection.State = ConnectionState.Closed Then
            '构造连接字串
            ConnString = "Provider=SQLOLEDB.1;Initial Catalog=" & _
                          DbName & ";Data Source=" & DataSource & _
                          ";Integrated Security=SSPI;Persist Security Info=False;"
            Try
                Connection.ConnectionString = ConnString
                Connection.Open()
            Catch ex As Exception
                ret = False
                DisplayError(ex)
            End Try
        End If
        SqlConnection = ret '返回函数结果
    End Function

    '接口OracleConnection ----- 连接到Oracle数据库(通过用户名和密码登录）
    'UserId ---- 用户名
    'Passord ----- 用户密码
    'DataSource ----- 要连接的Oracle实例的名字或者网络地址
    '如果是网络地址，IP地址后要加个端口号，如:190.190.200.100,1433
    '成功返回 True，否则返回 False
    Public Function OracleConnection(ByVal DataSource As String, ByVal UserId As String, ByVal Password As String) As Boolean

        Dim ret As Boolean = True
        '如果数据库连接没有打开，尝试打开数据库连接
        If Connection.State = ConnectionState.Closed Then
            '构造连接字串
            ConnString = "Provider=OraOLEDB.Oracle;Data Source=" & DataSource & _
                         ";User Id=" & UserId & ";Password=" & Password & ";"
            Try
                Connection.ConnectionString = ConnString
                Connection.Open()
            Catch ex As Exception
                ret = False
                DisplayError(ex)
            End Try
        End If
        OracleConnection = ret '返回函数结果
    End Function

    '接口OracleConnection ----- 连接到Oracle Server数据库(信任安全连接）
    'DataSource ----- 要连接的Oracle实例的名字
    '成功返回 True，否则返回 False
    Public Function OracleConnection(ByVal DataSource As String) As Boolean
        Dim ret As Boolean = True
        '如果数据库连接没有打开，尝试打开数据库连接
        If Connection.State = ConnectionState.Closed Then
            '构造连接字串
            ConnString = "Provider=OraOLEDB.Oracle;Data Source=" & DataSource & ";OSAuthent=1;"
            Try
                Connection.ConnectionString = ConnString
                Connection.Open()
            Catch ex As Exception
                ret = False
                DisplayError(ex)
            End Try
        End If
        OracleConnection = ret '返回函数结果
    End Function

    '接口ExcelConnection ----- 连接到Excel工作表
    'DbPath ----- .xls文件完整路径
    '成功返回 True，否则返回 False
    Public Function ExcelConnetion(ByVal DbPath As String) As Boolean
        Dim ret As Boolean = True
        '如果数据库连接没有打开，尝试打开数据库连接
        If Connection.State = ConnectionState.Closed Then
            '构造连接字串
            ConnString = "provider=Microsoft.Jet.OLEDB.4.0; Data Source=" & DbPath & _
            "; Extended Properties=Excel 8.0;"
            Try
                Connection.ConnectionString = ConnString
                Connection.Open()
            Catch ex As Exception
                ret = False
                DisplayError(ex)
            End Try
        End If
        ExcelConnetion = ret '返回函数结果
    End Function

    Public Sub New()
        '初始化类的成员变量
        Connection = New OleDbConnection
        Adapter = New OleDbDataAdapter
        Command = New OleDbCommand
        CommandBuilder = New OleDbCommandBuilder

        DeleteCommand = New OleDbCommand
        InsertCommand = New OleDbCommand
        SelectCommand = New OleDbCommand
        UpdateCommand = New OleDbCommand

        Command.Connection = Connection
        DeleteCommand.Connection = Connection
        InsertCommand.Connection = Connection
        SelectCommand.Connection = Connection
        UpdateCommand.Connection = Connection

    End Sub

    Protected Overrides Sub Finalize()
        '如果数据库处于连接状态，则关闭连接
        If Connection.State = ConnectionState.Open Then
            Try
                Connection.Close()
            Catch ex As Exception
                DisplayError(ex)
            End Try
        End If
    End Sub

End Class