VB operation Access Instance exercises--ATM Teller machine code snippet

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General
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Connect to the database (concatenate the database string and call the function):

Dim Con As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data source= atm.mdb"        Dim connconnection As Oledb.oledbconnection = New oledb.oledbconnection        connconnection.connectionstring = Con        connconnection.open ()

Verify user name password (that is, take the user name password entered on the interface to the database to match, if you can find the pass):

Private Function Userisvalid () as Boolean        ' Connect database        Dim Con as String = ' Provider=Microsoft.Jet.OLEDB.4.0;Data Source= atm.mdb "        Dim connconnection as Oledb.oledbconnection = New oledb.oledbconnection        connconnection.connectionstring = Con        connconnection.open ()

    ' Verify that the user name password exists        Dim strSQL as String = "SELECT * from accountinfo where Accountno = '" &       Trim (TextBox1.Text) & "' and Password = '" & Trim (TextBox2.Text) & "'"        Dim conncommand as Oledb.oledbcommand = New oledb.oledb Command (strSQL, connconnection)        Dim myreader as Oledb.oledbdatareader = Conncommand.executereader        ' If there is data        if Myreader.hasrows then            myreader.read () ' reads a row of data into reader            If Trim (TextBox1.Text) = myreader (1) and Trim ( TextBox2.Text) = myreader (2) then                connconnection.close ()                Return True            Else                connconnection.close ( Return                false            End If        connconnection.close ()        ' No data directly returns error return        false    end Function

Exit (in fact, all open windows are hidden, the login window will be displayed on it):

For each F as Form in Application.openforms            f.hide ()            frmlogin.show ()        Next

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Customer
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Withdrawal:

' Connect database        Dim Con As String = ' Provider=Microsoft.Jet.OLEDB.4.0;Data source= atm.mdb '        Dim connconnection As Oledb.oledbconnection = New oledb.oledbconnection        connconnection.connectionstring = Con        connconnection.open  ()        ' Modify amount (save money)        Dim sql as String = "Update accountinfo set Balance = Balance +" + TextBox1.Text + "where Accountno = ' "+ frmLogin.TextBox1.Text +" ' "        Dim cmd as Oledb.oledbcommand = New oledb.oledbcommand (sql, connconnection)        C Md. ExecuteNonQuery ()        ' record operation log        sql = ' INSERT INTO accountact (Accountno,lastopt,amount) VALUES (' "& Trim ( FrmLogin.TextBox1.Text) & "', '" & Trim (DateTime.Now.ToString ()) & "',        " & CType (TextBox1.Text, Double) & ")"        Dim cmd2 as Oledb.oledbcommand = New oledb.oledbcommand (sql, connconnection)        cmd2. ExecuteNonQuery ()        connconnection.close ()

Deposit:

' Connect database        Dim Con As String = ' Provider=Microsoft.Jet.OLEDB.4.0;Data source= atm.mdb '        Dim connconnection As Oledb.oledbconnection = New oledb.oledbconnection        connconnection.connectionstring = Con        connconnection.open  ()        ' Modify amount (take money)        Dim sql as String = "Update accountinfo set Balance = Balance-" + TextBox2.Text + "where Accountno = ' "+ frmLogin.TextBox1.Text +" ' "        Dim cmd as Oledb.oledbcommand = New oledb.oledbcommand (sql, connconnection)        C Md. ExecuteNonQuery ()        ' record operation log        sql = ' INSERT INTO accountact (Accountno,lastopt,amount) VALUES (' "& Trim ( FrmLogin.TextBox1.Text) & "', '" & Trim (DateTime.Now.ToString ()) & "',        " & CType (TextBox1.Text, Integer) & ")"        cmd = New oledb.oledbcommand (sql, connconnection)        cmd. ExecuteNonQuery ()        connconnection.close ()

Enquiry Account:

' Connect database        Dim Con As String = ' Provider=Microsoft.Jet.OLEDB.4.0;Data source= atm.mdb '        Dim connconnection As Oledb.oledbconnection = New oledb.oledbconnection        connconnection.connectionstring = Con        connconnection.open ()        Dim sql As String = "Select Balance from accountinfo where Accountno = '" + frmLogin.TextBox1.Text + "'"        Dim cm D as Oledb.oledbcommand = New oledb.oledbcommand (sql, connconnection)        Dim myreader as Oledb.oledbdatareader = cmd. ExecuteReader        If Myreader.hasrows then            myreader.read ()            Label1.Text = myreader (0)        Else            MessageBox.Show ("Account information not found")        End If        connconnection.close ()

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Administrator
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Logging the Operation log:

sql = "INSERT into Accountact (Accountno,lastopt,amount) VALUES ('" & Trim (FrmLogin.TextBox1.Text) & "', '" & T Rim (DateTime.Now.ToString ()) & "'," & CType (TextBox1.Text, Integer) & ")"        cmd = New Oledb.oledbcommand (s QL, connconnection)        cmd. ExecuteNonQuery ()        connconnection.close ()

To view all operation logs:

' Connect database        Dim Con As String = ' Provider=Microsoft.Jet.OLEDB.4.0;Data source= atm.mdb '        Dim connconnection As Oledb.oledbconnection = New oledb.oledbconnection        connconnection.connectionstring = Con        connconnection.open ()        ' Take the data of the query out and put it into data set        Dim strSQL as String = "SELECT * from Accountact"        Dim mydataset as DataSet = New DataS ET ()        Dim myadapter as Oledb.oledbdataadapter = New oledb.oledbdataadapter (strSQL, connconnection)        Myadapter.fill (myDataSet, "Accountact")        connconnection.close ()        ' pulls data out of the dataset to display on the control ()        Datagridview1.datasource = mydataset.tables (0)        Datagridview1.autosizecolumnsmode = Datagridviewautosizecolumnsmode.allcells

View all user accounts

' Connect database        Dim Con As String = ' Provider=Microsoft.Jet.OLEDB.4.0;Data source= atm.mdb '        Dim connconnection As Oledb.oledbconnection = New oledb.oledbconnection        connconnection.connectionstring = Con        connconnection.open ()        ' Take the data from the query and put it into data set        Dim strSQL As String = "SELECT * from AccountInfo"        Dim mydataset as DataSet = New data Set ()        Dim myadapter as Oledb.oledbdataadapter = New oledb.oledbdataadapter (strSQL, connconnection)        Myadapter.fill (myDataSet, "AccountInfo")        connconnection.close ()        ' pulls data out of the dataset to display on the control ()        Datagridview1.datasource = mydataset.tables (0)        Datagridview1.autosizecolumnsmode = Datagridviewautosizecolumnsmode.allcells

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