frm_renewalbook.vb

是关于图书管理系统的用vb.net 和access开发的

Imports System.Data.OleDb

Public Class frm_renewalBook

    Dim myConnection As New OleDbConnection("provider=Microsoft.Jet.OLEDB.4.0; Data source=D:\library.mdb")
    Dim myCommand As OleDbCommand
    Dim myReader As OleDbDataReader

    Dim maxRenewalNo As String
    Dim alrRenewalNo As String
    Dim readerTypeCode As String
    Dim updateRenewalNo As Integer
    Dim freezeStatus As Boolean = False

    Dim newDueDate As Date

    Private Sub readernotxt_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles readerNotxt.KeyPress

        If e.KeyChar = ChrW(System.Windows.Forms.Keys.Enter) Then

            If readerNotxt.Text <> "" Then
                If checkValidReader() Then
                    ISBNtxt.Focus()
                    renewalbt.Enabled = True
                Else
                    If freezeStatus = False Then
                        MsgBox("Invalid reader ID!")
                        readerNotxt.Focus()
                        readerNotxt.SelectAll()
                        renewalbt.Enabled = False
                    End If
                End If
            Else
                MsgBox("Reader no can not be empty!")
                renewalbt.Enabled = False
            End If
        End If
        freezeStatus = False
    End Sub
    Private Sub isbntxt_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles ISBNtxt.KeyPress

        If e.KeyChar = ChrW(System.Windows.Forms.Keys.Enter) Then
            If ISBNtxt.Text <> "" Then
                If checkValidBook() Then

                    If alrInRentRec() = False Then
                        MsgBox("Reader has not borrowed this book yet,so need not to renewal! ")
                        renewalbt.Enabled = False
                    Else
                        setMaxRenewal()
                        setAlrRenewalNoAndDate()
                        displayRewInfo()
                        admNotxt.Focus()
                        renewalbt.Enabled = True
                    End If
                Else
                    MsgBox("Invalid book ISBN!")
                    ISBNtxt.Focus()
                    ISBNtxt.SelectAll()
                    renewalbt.Enabled = False
                End If




                Else
                    MsgBox("ISBN no can not be empty!")
                    renewalbt.Enabled = False
                End If
            End If

    End Sub

    Function alrInRentRec()

        Dim temp As String = ""
        myConnection.Open()
        myCommand = New OleDbCommand("select * from RentBook where ISBN='" & ISBNtxt.Text & _
        "'and ReaderNo='" & readerNotxt.Text & "'", myConnection)
        myReader = myCommand.ExecuteReader()


        While myReader.Read
            temp = myReader("ISBN")
        End While

        myConnection.Close()
        myCommand.Dispose()
        myReader.Close()

        If temp = "" Then
            Return False
        Else

            Return True
        End If
    End Function
    Function checkValidBook() As Boolean

        Dim isbn As String = ""
     
        myConnection.Open()
        myCommand = New OleDbCommand("select * from BookDetails where ISBN='" & ISBNtxt.Text & "'", myConnection)
        myReader = myCommand.ExecuteReader()


        While myReader.Read
            isbn = myReader("ISBN")
        End While

        myConnection.Close()
        myCommand.Dispose()
        myReader.Close()

        If isbn = "" Then
            Return False
        Else

            Return True

        End If
    End Function

    Function checkValidReader() As Boolean

        Dim readerNo As String = ""

        Dim status As String = ""

        myConnection.Open()
        myCommand = New OleDbCommand("select * from ReaderDetails where ReaderNo='" & readerNotxt.Text & "'", myConnection)
        myReader = myCommand.ExecuteReader()


        While myReader.Read
            readerNo = myReader("ReaderNo")
            readerTypeCode = myReader("ReaderTypeCode")
            status = myReader("status")
        End While

        myConnection.Close()
        myCommand.Dispose()
        myReader.Close()


        If readerNo = "" Then
            Return False
        ElseIf status = "freeze" Then
            freezeStatus = True
            MsgBox("The user is frozen now, can not be serviced!")
            renewalbt.Enabled = False
            Return False
        Else
            Return True
        End If

    End Function
    Sub setMaxRenewal()

        
        myConnection.Open()
        myCommand = New OleDbCommand("select * from ReaderType where ReaderTypeCode='" & readerTypeCode & "'", myConnection)
        myReader = myCommand.ExecuteReader()

        While myReader.Read
            maxRenewalNo = myReader("RenewalNo")
        End While

        myConnection.Close()
        myCommand.Dispose()
        myReader.Close()



    End Sub
    Sub setAlrRenewalNoAndDate()
        Dim oldDueDate As Date

        myConnection.Open()
        myCommand = New OleDbCommand("select * from RentBook where ReaderNo='" & readerNotxt.Text & _
        "' and ISBN ='" & ISBNtxt.Text & "'", myConnection)
        myReader = myCommand.ExecuteReader()

        While myReader.Read
            alrRenewalNo = myReader("AlrRenewalNo")
            oldDueDate = Date.Parse(myReader("Duedate"))
        End While

        updateRenewalNo = Integer.Parse(alrRenewalNo) + 1

        newDueDate = oldDueDate.AddDays(10)

        myConnection.Close()
        myCommand.Dispose()
        myReader.Close()

    End Sub
    Sub displayRewInfo()

        maxRewNotxt.Text = maxRenewalNo
        alrRewNotxt.Text = alrRenewalNo
       
    End Sub

    Private Sub renewalbt_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles renewalbt.Click

        If readerNotxt.Text = "" Or ISBNtxt.Text = "" Or admNotxt.Text = "" Or passwordtxt.Text = "" Then
            MsgBox("Information is not enough!")
          
        Else
            renewal()
        End If

    End Sub
    Private Sub passwordtxt_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles passwordtxt.KeyPress

        If e.KeyChar = ChrW(System.Windows.Forms.Keys.Enter) Then
            checkValidAdm()
        End If
    End Sub
    Function checkValidAdm() As Boolean

        Dim admNo As String = ""
        Dim password As String = ""


        myConnection.Open()
        myCommand = New OleDbCommand("select * from Administrator where AdmNo = '" & admNotxt.Text & _
           "'", myConnection)
        myReader = myCommand.ExecuteReader()

        While myReader.Read
            admNo = myReader("AdmNo")
            password = myReader("Password")
        End While

        myConnection.Close()
        myReader.Close()
        myCommand.Dispose()

        If admNo = "" Then
            MsgBox("Invalid Administrator ID!")
            admNotxt.Clear()
            admNotxt.Focus()
            passwordtxt.Clear()
            renewalbt.Enabled = False
        Else

            If password = passwordtxt.Text Then
                renewalbt.Enabled = True
                Return True
            Else

                MsgBox("Invalid Administrator Password!")
                passwordtxt.Focus()
                passwordtxt.SelectAll()
                renewalbt.Enabled = False
                Return False

            End If
        End If
    End Function
    Sub renewal()

        If Integer.Parse(alrRewNotxt.Text) >= Integer.Parse(maxRewNotxt.Text) Then
            MsgBox("Can not renewal any more book!")
            renewalbt.Enabled = False
        Else
            myConnection.Open()
            myCommand = New OleDbCommand("Update RentBook set AlrRenewalNO= " & updateRenewalNo & _
",DueDate=#" & newDueDate.ToShortDateString & "# where ReaderNo='" & _
            readerNotxt.Text & "' and ISBN ='" & ISBNtxt.Text & "'", myConnection)

            myReader = myCommand.ExecuteReader()

            While myReader.Read
                alrRenewalNo = myReader("AlrRenewalNo")
            End While

            myConnection.Close()
            myCommand.Dispose()
            myReader.Close()

            MsgBox("Renewal successfully!")
        End If

    End Sub

    Private Sub exitbt_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles exitbt.Click
        Me.Close()
    End Sub

    Private Sub resetbt_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles resetbt.Click
        readerNotxt.Clear()
        ISBNtxt.Clear()
        maxRewNotxt.Clear()
        alrRewNotxt.Clear()
        admNotxt.Clear()
        passwordtxt.Clear()

        readerNotxt.Focus()
        renewalbt.Enabled = True

    End Sub
End Class