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Concatenation using + or  &

Posted on 2007-11-30
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Last Modified: 2013-11-26
The concatenation going on here:
 
Me.ProductIDTable. Columns.Add( "FullProduct" , GetType(String) ,
"ProductName + '-' + Category + '-' + Measure + '-' + OzLtr + '-' +
SupplierName" )
 
Please explain why I can't use the & symbol to concatenate but can use the +. An in depth expanation would help. The fields in the database are being concatenated, but is appears to me that FullProduct is a string and I should be able to convert it to &...
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Question by:mindserve
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Expert Comment

by:Guy Hengel [angelIII / a3]
ID: 20382591
are you aware that you have " " around the whole expression, so the + will not be taken into account at all?!
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Author Comment

by:mindserve
ID: 20383234
But it does seem to be taken into consideration, the code does function with the + exactly as you see it above.
If it did not have the " around it, you get an error and the code won't run at all.


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LVL 1

Author Comment

by:mindserve
ID: 20383270
Anyway, the question would assume that the code I have works  so again :

Please explain why I can't use the & symbol to concatenate but can use the +. An in depth expanation would help. The fields in the database are being concatenated, but is appears to me that FullProduct is a string and I should be able to convert it to &.
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Author Comment

by:mindserve
ID: 20383306
Here is the code from the small application I have. It all works....Just need to know why I can't use the & instead of the + . I am concatenating the fields in the database, but it seems that they are a string in how its formatted in the code.
Option Strict On 'leave strict and explict turned on
Option Explicit On
Imports System.Data
Imports System.Data.OleDb
 
Public Class FrmEmployees
 
 
 
    Private formLoading As Boolean
    Private EmployeeRowPosition As Integer = 0
    Dim EmployeeIDConnection As OleDbConnection
    Dim EmployeeIDCommand As OleDbCommand
    Dim EmployeeIDAdapter As OleDbDataAdapter
    Dim EmployeeIDTable As DataTable
    Dim EmployeeIDManager As CurrencyManager
 
    Dim MyState As String
    Dim MyBookmark As Integer
 
    Dim LastNameList As DataTable
    Private LastNameManager As CurrencyManager
    Private EmployeeDeleteCommand As OleDbCommand
 
 
    '--------------------------------------------------------------------
    Private Sub employees_FormClosing(ByVal sender As Object, ByVal e As System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing
1:      If MyState = "Edit" Or MyState = "Add" Then
2:          MessageBox.Show("You must finish the current edit before stopping.", "", MessageBoxButtons.OK, MessageBoxIcon.Information)
3:          e.Cancel = True
4:      Else
5:          Try
                'save the updateEmployeeID table
6:              Dim EmployeeIDAdapterCommands As New OleDbCommandBuilder(EmployeeIDAdapter)
7:              EmployeeIDAdapter.Update(EmployeeIDTable)
8:          Catch ex As Exception
9:              MessageBox.Show(ex.Message, "Error Saving Database", MessageBoxButtons.OK, MessageBoxIcon.Error)
10:         End Try
            'close the connection
11:         EmployeeIDConnection.Close()
            'dispose of the objects
12:         EmployeeIDCommand.Dispose()
13:         EmployeeIDAdapter.Dispose()
14:         EmployeeIDTable.Dispose()
15:     End If
    End Sub
 
    Private Sub Employees_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
 
        'initialize objects
1:      EmployeeIDConnection = New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0; Data Source = " + Application.StartupPath + "\shx.mdb")
 
2:      Me.LastNameList = New DataTable
 
3:      Me.EmployeeIDTable = New DataTable
 
 
4:      Me.EmployeeIDCommand = New OleDbCommand("SELECT * FROM Employees")
5:      Me.EmployeeIDCommand.Connection = Me.EmployeeIDConnection
6:      Me.EmployeeIDAdapter = New OleDbDataAdapter
7:      Me.EmployeeIDAdapter.SelectCommand = Me.EmployeeIDCommand
 
8:      Dim cmdBuilder As New OleDbCommandBuilder(Me.EmployeeIDAdapter)
        'this will get the right EmployeeID value during Insert action
9:      AddHandler EmployeeIDAdapter.RowUpdated, AddressOf EmployeeIDAdapter_RowUpdated
 
        'keep this command and use it later, see Delete method
10:     Me.EmployeeDeleteCommand = cmdBuilder.GetDeleteCommand(True)
        'there are 57 paramenters, we need only one
11:     Me.EmployeeDeleteCommand.Parameters.Clear()
 
12:     Dim idParam As New OleDbParameter()
13:     idParam.ParameterName = "Original_EmployeeID"
14:     idParam.OleDbType = OleDbType.Integer
15:     idParam.SourceColumn = "EmployeeID"
16:     idParam.SourceVersion = DataRowVersion.Original 'very important, makes sure the value is the one loaded from the database
17:     Me.EmployeeDeleteCommand.Parameters.Add(idParam)
        'now change the SQL Statement to mach the new parameter collection
18:     Me.EmployeeDeleteCommand.CommandText = "DELETE FROM Employees WHERE EmployeeID=?"
 
 
19:     Me.EmployeeIDManager = DirectCast(Me.BindingContext(EmployeeIDTable), CurrencyManager)
20:     AddHandler EmployeeIDManager.PositionChanged, AddressOf EmployeeIDManager_PositionChanged
 
        'add full name column
21:     Dim colLastName As New DataGridViewTextBoxColumn
22:     colLastName.DataPropertyName = "FullName"
23:     Me.dgEmp.Columns.Add(colLastName)
24:     Me.dgEmp.AutoGenerateColumns = False 'to make sure that only FullName column will be displayed
25:     Me.dgEmp.DataSource = Me.EmployeeIDTable 'this way the grid and the controls will be bound to the same data
 
 
26:     Me.LastNameManager = DirectCast(Me.BindingContext(Me.LastNameList), CurrencyManager)
        'Load last names
27:     Me.FillLastNames()
        'add a primary key,it will load data faster
28:     Me.LastNameList.PrimaryKey = New DataColumn() {Me.LastNameList.Columns(0)}
        'AddHandler LastNameManager.PositionChanged, AddressOf LastNameList_PositionChanged
        'AddHandler LastNameManager.CurrentChanged, AddressOf LastNameList_PositionChanged
        'AddHandler LastNameManager.CurrentItemChanged, AddressOf LastNameList_PositionChanged
        'AddHandler LastNameManager.MetaDataChanged, AddressOf LastNameList_PositionChanged
 
29:     Me.FillEmployees()
 
30:     Try
            'Concatenate the first and last name of the customer.
31:         Me.EmployeeIDTable.Columns.Add("FullName", GetType(String), "LastName + ', ' + FirstName")
            'set the default value of Dependents column
            '//////////////////////////////////////////////////////////////////////
            '32:         Dim myDataView As DataView = New DataView(Me.EmployeeIDTable) 'JHG
            '33:         myDataView.Sort = "LastName ASC, FirstName ASC" 'JHG
            '34:         Me.dgEmp.DataSource = myDataView 'JHG
            EmployeeIDTable.DefaultView.Sort = "FirstName"
            'JHG the problem is that it does not bind now to the textboxes.But it does sort the grid...:)
            'It should load and bind to textboxes in alphabetical order.
            '//////////////////////////////////////////////////////////////////////////////////
35:         Me.EmployeeIDTable.Columns("Dependents").DefaultValue = 1
36:     Catch ex As Exception
37:         Console.WriteLine()
38:     End Try
 
 
        'bind controls
39:     Me.BindControls()
 
 
 
        'show initial photo
40:     Call ShowUnbound()
41:     Call SetState("View")
        'Call ShowPhoto()
42:     Me.Top = 80
 
        'txtStatus.Text = CStr(CDbl(ComboBox3.SelectedIndex.ToString) + 1) & " of " & EmployeeIDManager.Count - 0
    End Sub
 
#Region "Added 09/20/2007"
 
    ''' <summary>
    ''' Load Last Names
    ''' </summary>
    ''' <remarks></remarks>
    Public Sub FillLastNames()
 
        '"Using" statement makes sure the object is disposed even if errors occur
1:      Using adapter As New OleDbDataAdapter
2:          Using cmd As New OleDbCommand("SELECT DISTINCT LastName FROM Employees ORDER BY LastName") '"DISTINCT" keyword doesn't load duplicates
3:              cmd.Connection = Me.EmployeeIDConnection
4:              adapter.SelectCommand = cmd
                'fill last name list
5:              adapter.Fill(Me.LastNameList)
                'fill the combobox
6:              Me.ComboBox3.DataSource = Me.LastNameList
7:              Me.ComboBox3.ValueMember = "LastName"
8:              Me.ComboBox3.DisplayMember = "LastName"
                'after this, the SelectedIndexChanged event is fired, so the current data will be loaded:
                'ComboBox3_SelectedIndexChanged will call FillEmployees method
 
9:          End Using
10:     End Using
 
 
    End Sub
 
    ''' <summary>
    ''' Fills EmployeeIDTable filtered by the current value of the LastNames combobox
    ''' </summary>
    ''' <remarks></remarks>
    Public Sub FillEmployees()
1:      Me.FillEmployees(Me.ComboBox3.Text)
    End Sub
 
    Public Sub FillEmployees(ByVal searchTerm As String)
1:      Me.FillEmployees(searchTerm, "LastName", "=")
    End Sub
 
    ''' <summary>
    ''' Fills the EmployeeIDTable using a search term, field (usualy LastName or FirstName) and an operator("LIKE" or "=")
    ''' </summary>
    ''' <param name="searchTerm"></param>
    ''' <param name="field"></param>
    ''' <param name="operator"></param>
    ''' <remarks></remarks>
    Public Sub FillEmployees(ByVal searchTerm As String, ByVal field As String, ByVal [operator] As String)
1:      Try
2:          Dim cmdText As String = String.Empty
            'build the sql statement;it will also create the FullName column
3:          Select Case [operator]
                Case "LIKE"
4:                  cmdText = "SELECT * FROM Employees WHERE " & field & " LIKE '" & searchTerm & "%' ORDER BY " & field
5:              Case "="
6:                  cmdText = "SELECT * FROM Employees WHERE " & field & " = '" & searchTerm & "' ORDER BY " & field
7:                  End Select
8:          If Not String.IsNullOrEmpty(cmdText) Then
9:              Me.EmployeeIDCommand.CommandText = cmdText
                'clear current data
10:             Me.EmployeeIDTable.Clear()
11:             Me.EmployeeIDAdapter.Fill(Me.EmployeeIDTable)
12:         End If
 
 
13:         Me.ShowUnbound()
 
14:         Me.lblSearchStatus.Text = ""
15:     Catch ex As Exception
16:         Console.WriteLine(ex.ToString)
17:     End Try
 
    End Sub
 
    Private Sub btnSearchCustomerNames_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSearchCustomerNames.Click
1:      Control.CheckForIllegalCrossThreadCalls = False 'to avoid exceptions, this can be set only once in the constructor
 
        'more options can be added here:disable other controls, add a cancel button etc.
2:      Me.lblSearchStatus.Text = "Searching. Please wait ..."
        'create a new thread
3:      Dim t As New Threading.Thread(New Threading.ParameterizedThreadStart(AddressOf Me.FillEmployeesSafe))
        'start the thread with parameters
4:      t.Start(New Object() {Me.txtSearchTerm.Text, Me.cmbSearchField.Text, Me.cmbOperator.Text})
        'make sure the ui is not blocked
5:      Do While t.IsAlive
6:          Application.DoEvents()
7:      Loop
 
        'if you want to run this as it was before, just comment or delete the code above and uncomment the following line
        'Me.FillEmployees(Me.txtSearchTerm.Text, Me.cmbSearchField.Text, Me.cmbOperator.Text)
    End Sub
 
    ''' <summary>
    ''' The same as FillEmployees.Used when performing search in another thread
    ''' </summary>
    ''' <param name="params"></param>
    ''' <remarks></remarks>
    Private Sub FillEmployeesSafe(ByVal params As Object)
1:      Dim parameters As Object() = CType(params, [Object]())
2:      Me.FillEmployees(CStr(parameters(0)), CStr(parameters(1)), CStr(parameters(2)))
    End Sub
 
    Public Sub BindControls()
1:      txtFirstName.DataBindings.Add("Text", EmployeeIDTable, "FirstName")
2:      txtLastName.DataBindings.Add("Text", EmployeeIDTable, "LastName")
        ' txtEmployeeName.DataBindings.Add("Text", EmployeeIDTable, "EmployeeName")
3:      txtMI.DataBindings.Add("Text", EmployeeIDTable, "MI")
4:      TxtEmployeeID.DataBindings.Add("Text", EmployeeIDTable, "EmployeeID")
5:      txtTitle.DataBindings.Add("Text", EmployeeIDTable, "Title")
6:      TxtHireDate.DataBindings.Add("Text", EmployeeIDTable, "HireDate")
7:      TxtTerminationDate.DataBindings.Add("Text", EmployeeIDTable, "TerminationDate")
8:      RTFReasonForTermination.DataBindings.Add("Text", EmployeeIDTable, "ReasonForTermination")
9:      txtAddress.DataBindings.Add("Text", EmployeeIDTable, "Address")
        '/////////////////////////////////////////////////////////////////////////
10:     txtCity.DataBindings.Add("Text", EmployeeIDTable, "City")
11:     txtState.DataBindings.Add("Text", EmployeeIDTable, "State")
12:     txtZip.DataBindings.Add("Text", EmployeeIDTable, "ZipCode")
13:     txtBirthDate.DataBindings.Add("Text", EmployeeIDTable, "BirthDate")
14:     lblPhotoFileBefore.DataBindings.Add("Text", EmployeeIDTable, "Photo")
        '///////////////////////
15:     txtOccupation.DataBindings.Add("Text", EmployeeIDTable, "EmployeeCategory")
16:     RTFNotes.DataBindings.Add("Text", EmployeeIDTable, "Notes")
17:     txtReferredBy.DataBindings.Add("Text", EmployeeIDTable, "ReportsTo")
18:     txtHomePhone.DataBindings.Add("Text", EmployeeIDTable, "HomePhone")
19:     txtWorkPhone.DataBindings.Add("Text", EmployeeIDTable, "EmgPhone")
20:     txtCellPhone.DataBindings.Add("Text", EmployeeIDTable, "EmgContact")
 
        '////////////////////////////////////////////////////////////////////////////////////////////
21:     txtSS.DataBindings.Add("Text", EmployeeIDTable, "EmployeeSS")
22:     TxtPayrollID.DataBindings.Add("Text", EmployeeIDTable, "PayrollID")
23:     TxtEmpSchedID.DataBindings.Add("Text", EmployeeIDTable, "EmpSchedID")
24:     TxtPayRate.DataBindings.Add("Text", EmployeeIDTable, "PayRate")
25:     txtRate.DataBindings.Add("Text", EmployeeIDTable, "TypeRate")
26:     TxtMarriedEmp.DataBindings.Add("Text", EmployeeIDTable, "MarriedEmp")
27:     TxtNotMarried.DataBindings.Add("Text", EmployeeIDTable, "NotMarried") 'This is what is causing the update error message,,but why?See second tabNOTE: Temporarily removed it from the select statement.
28:     TxtDependents.DataBindings.Add("Text", EmployeeIDTable, "Dependents")
        '/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 
29:     Me.EmployeeIDTable.Columns("Male").DefaultValue = False
30:     Me.EmployeeIDTable.Columns("Female").DefaultValue = False
31:     RBFemale.DataBindings.Add("Checked", EmployeeIDTable, "Female")
32:     RBMale.DataBindings.Add("Checked", EmployeeIDTable, "Male")
    End Sub
 
    ''' <summary>
    ''' This is fired when the user moves to another row in the grid
    ''' </summary>
    ''' <param name="sender"></param>
    ''' <param name="e"></param>
    ''' <remarks></remarks>
    Private Sub EmployeeIDManager_PositionChanged(ByVal sender As Object, ByVal e As EventArgs)
1:      Me.ShowUnbound()
    End Sub
 
    Private Sub LastNameList_PositionChanged(ByVal sender As Object, ByVal e As EventArgs)
1:      Me.FillEmployees()
    End Sub
 
    ''' <summary>
    ''' Saves the current record
    ''' </summary>
    ''' <remarks></remarks>
    Public Sub Save()
1:      Me.Validate()
2:      Me.EmployeeIDManager.EndCurrentEdit()
3:      If txtLastName.Text.Trim = "" Or txtFirstName.Text.Trim = "" Or txtTitle.Text.Trim = "" Then
 
4:          ErrorProviderEmployees.SetError(txtLastName, "You must supply a Last Name for the Employee")
5:          ErrorProviderEmployees.SetError(txtFirstName, "You must supply a First Name for the Employee")
6:          ErrorProviderEmployees.SetError(txtTitle, "You must supply a Title for the Employee")
7:          MessageBox.Show("You must have a Last Name, FirstName and Title entered before you can save.", "Save Error", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
8:          txtLastName.Focus()
9:          ErrorProviderEmployees.SetError(txtLastName, "")
10:         ErrorProviderEmployees.SetError(txtFirstName, "")
11:         ErrorProviderEmployees.SetError(txtTitle, "")
12:         Exit Sub
13:     End If
 
14:     Try
15:         Dim drv As DataRowView = CType(Me.EmployeeIDManager.Current(), DataRowView)
16:         Dim row As DataRow = drv.Row
 
            'keep the previous Last Name, if an existing row is updated
17:         Dim origLastName As String = String.Empty
18:         If row.HasVersion(DataRowVersion.Original) Then 'it's not a new row
19:             origLastName = CStr(row("LastName", DataRowVersion.Original))
20:         End If
 
21:         If Me.EmployeeIDAdapter.Update(New DataRow() {row}) > 0 Then
22:             Dim lastName As String = CStr(row("LastName"))
23:             If lastName <> origLastName Then 'Last Name was changed, so add it in the list
24:                 If Me.LastNameList.Rows.Find(lastName) Is Nothing Then
25:                     Me.LastNameList.Rows.Add(New Object() {lastName})
26:                 End If
 
27:                 If origLastName <> String.Empty Then 'existing row
                        'check if the old Last Name should be in the list
28:                     Using cmd As New OleDbCommand("SELECT DISTINCT LastName FROM Employees WHERE LastName ='" & origLastName & "'") '"DISTINCT" keyword doesn't load duplicates
29:                         cmd.Connection = Me.EmployeeIDConnection
30:                         Try
31:                             cmd.Connection.Open()
32:                             Dim result As Object = cmd.ExecuteScalar
33:                             If result Is Nothing Then 'there are no records matching origLastName
                                    'delete it from the list
34:                                 Dim lnRow As DataRow = Me.LastNameList.Rows.Find(origLastName) 'this works only with primary key columns
35:                                 If lnRow IsNot Nothing Then
36:                                     Me.LastNameList.Rows.Remove(lnRow)
37:                                     Me.LastNameList.AcceptChanges()
38:                                 End If
39:                             End If
40:                         Catch ex As Exception
41:                             Console.WriteLine()
42:                         Finally
43:                             If Me.EmployeeIDConnection.State <> ConnectionState.Closed Then
44:                                 Me.EmployeeIDConnection.Close()
45:                             End If
46:                         End Try
 
 
47:                     End Using
 
48:                 End If
 
 
49:             End If
 
 
 
 
 
50:         End If
51:         Call ShowUnbound()
52:         Call SetState("View")
53:         Call controltabs()
54:     Catch ex As Exception
55:         Console.WriteLine(ex.ToString)
56:     End Try
 
    End Sub
 
    Public Sub Delete()
 
1:      Try
            'get the current row
2:          Dim drv As DataRowView = CType(Me.EmployeeIDManager.Current(), DataRowView)
 
3:          If drv.IsNew Then 'if it's new, it means there is not saved in the database so there's nothing to delete: just cancel the action
4:              Me.btnCancel.PerformClick()
5:              Exit Sub
6:          End If
 
            'it will be used after the delete action to check if this name should be in the list
7:          Dim lastName As String = CStr(drv("LastName"))
 
8:          Dim id As Integer = CInt(drv("EmployeeID"))
            'set the value of the parameter
9:          Me.EmployeeDeleteCommand.Parameters("Original_EmployeeID").Value = id
            'use EmployeeDeleteCommand
10:         Me.EmployeeDeleteCommand.Connection.Open()
 
11:         If Me.EmployeeDeleteCommand.ExecuteNonQuery > 0 Then 'the record was deleted from database
                'now delete the row from the datatable
12:             drv.Delete()
                'now the row still exists in the DataTable(EmployeeIDTable), but it has its RowState property = Deleted
13:             Me.EmployeeIDTable.AcceptChanges() 'to make sure the row is deleted for ever
 
                'check if Last Name still should be there
14:             If Not String.IsNullOrEmpty(lastName) Then 'this should never happen, since LastName is validated during save
 
15:                 Using cmd As New OleDbCommand("SELECT DISTINCT LastName FROM Employees WHERE LastName ='" & lastName & "'") '"DISTINCT" keyword doesn't load duplicates
16:                     cmd.Connection = Me.EmployeeIDConnection
 
                        'the connection is already open
17:                     Dim result As Object = cmd.ExecuteScalar
18:                     If result Is Nothing Then 'there are no records matching lastName
                            'delete it from the list
19:                         Dim lnRow As DataRow = Me.LastNameList.Rows.Find(lastName) 'this works only with primary key columns
20:                         If lnRow IsNot Nothing Then
21:                             Me.LastNameList.Rows.Remove(lnRow)
22:                             Me.LastNameList.AcceptChanges()
23:                             Me.FillEmployees()
24:                         End If
 
25:                     End If
 
26:                 End Using
 
27:             End If
 
28:             Call ShowUnbound()
29:             Call SetState("View")
30:             Call controltabs()
 
31:         End If
 
 
32:     Catch ex As Exception
33:         Console.WriteLine(ex.ToString)
34:     Finally
            'this code will run even if there are exceptions
35:         If Me.EmployeeDeleteCommand.Connection.State <> ConnectionState.Closed Then
36:             Me.EmployeeDeleteCommand.Connection.Close()
37:         End If
38:     End Try
    End Sub
 
    ''' <summary>
    ''' Gets the value of the primary key from the database and updates the EmployeeID in DataRow
    ''' This way concurrency errors are avoided
    ''' </summary>
    ''' <param name="sender"></param>
    ''' <param name="e"></param>
    ''' <remarks></remarks>
    Private Sub EmployeeIDAdapter_RowUpdated(ByVal sender As Object, ByVal e As OleDb.OleDbRowUpdatedEventArgs)
1:      If e.Status = UpdateStatus.Continue AndAlso e.StatementType = StatementType.Insert Then
            'create an OleDbCommand which will get the value of the primary key
2:          Using cmdIdentity As New OleDb.OleDbCommand("SELECT @@IDENTITY", Me.EmployeeIDConnection)
3:              Dim id As Integer = CInt(cmdIdentity.ExecuteScalar) 'this is the new value of EmployeeID from the database
 
                'get the current EmployeeID of the data row
4:              Dim cId As Integer
5:              If Not e.Row.IsNull("EmployeeID") Then
6:                  cId = CInt(e.Row("EmployeeID"))
7:              End If
 
8:              If id <> cId Then
9:                  e.Row("EmployeeID") = id 'set the new value
10:                 e.Row.EndEdit()
11:             End If
12:             Dim ad As OleDb.OleDbDataAdapter = DirectCast(sender, OleDb.OleDbDataAdapter)
13:             If ad.AcceptChangesDuringUpdate Then
14:                 e.Row.AcceptChanges()
15:             End If
16:         End Using
17:     End If
    End Sub
 
#End Region
 
 
    Private Sub ShowPhoto()
1:      If lblPhotoFileBefore.Text <> "" Then
2:          Try
3:              Photo.Image = Image.FromFile(lblPhotoFileBefore.Text)
4:          Catch ex As Exception
5:              MessageBox.Show(ex.Message, "Error Loading Photo", MessageBoxButtons.OK, MessageBoxIcon.Error)
6:          End Try
7:      Else
8:          Photo.Image = Nothing
9:      End If
 
 
    End Sub
 
    Private Sub btnFirst_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnFirst.Click
1:      EmployeeIDManager.Position = 0
2:      Call ShowUnbound()
 
    End Sub
 
    Private Sub btnPrevious_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnPrevious.Click
1:      EmployeeIDManager.Position -= 1
2:      Call ShowUnbound()
    End Sub
 
    Private Sub btnNext_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnNext.Click
1:      EmployeeIDManager.Position += 1
2:      Call ShowUnbound()
 
    End Sub
 
    Private Sub btnLast_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnLast.Click
1:      EmployeeIDManager.Position = EmployeeIDManager.Count - 1
2:      Call ShowUnbound()
 
    End Sub
    Private Sub SetState(ByVal AppState As String)
 
1:      Try
2:          MyState = AppState
3:          Select Case AppState
                Case "View"
4:                  btnFirst.Enabled = True
5:                  btnPrevious.Enabled = True
6:                  btnNext.Enabled = True
7:                  btnLast.Enabled = True
8:                  btnEdit.Enabled = True
9:                  btnSave.Enabled = False
10:                 btnCancel.Enabled = False
11:                 btnAdd.Enabled = True
12:                 btnDelete.Enabled = True
13:                 btnPrint.Enabled = True
14:                 btnExit.Enabled = True
15:                 txtFirstName.ReadOnly = True
16:                 txtLastName.ReadOnly = True
 
                    'dtpBirthdate.Enabled = False
17:                 btnLoadPhoto.Enabled = False
                    'ErrorProviderEmployees.Clear()
 
 
18:                 RBFemale.Enabled = True
19:                 RBMale.Enabled = True
20:                 Me.dgEmp.Enabled = True
 
21:             Case "Add", "Edit"
 
22:                 btnFirst.Enabled = False
23:                 btnPrevious.Enabled = False
24:                 btnNext.Enabled = False
25:                 btnLast.Enabled = False
26:                 btnEdit.Enabled = False
27:                 btnSave.Enabled = True
28:                 btnCancel.Enabled = True
29:                 btnAdd.Enabled = False
30:                 btnDelete.Enabled = False
31:                 btnPrint.Enabled = False
32:                 btnExit.Enabled = False
33:                 txtFirstName.ReadOnly = False
34:                 txtLastName.ReadOnly = False
 
                    'dtpBirthdate.Enabled = True
 
35:                 btnLoadPhoto.Enabled = True
                    ''CheckHome.Enabled = True
 
 
 
36:                 RBFemale.Enabled = True
37:                 RBMale.Enabled = True
38:                 Me.dgEmp.Enabled = False
 
39:                 End Select
 
40:         txtLastName.Focus()
 
            'txtStatus.Text = CStr(CDbl(ComboBox3.SelectedIndex.ToString) + 1) & " of " & EmployeeIDManager.Count - 0
41:     Catch ex As Exception
42:         System.Windows.Forms.MessageBox.Show(ex.ToString)
43:     End Try
    End Sub
 
    Private Sub btnEdit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnEdit.Click
1:      Call SetState("Edit")
 
    End Sub
 
    Private Sub btnSave_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSave.Click
 
1:      Me.Save()
        'If txtLastName.Text.Trim = "" Or txtFirstName.Text.Trim = "" Or txtTitle.Text.Trim = "" Then
 
        '    ErrorProviderEmployees.SetError(txtLastName, "You must supply a Last Name for the Employee")
        '    ErrorProviderEmployees.SetError(txtFirstName, "You must supply a First Name for the Employee")
        '    ErrorProviderEmployees.SetError(txtTitle, "You must supply a Title for the Employee")
        '    MessageBox.Show("You must have a Last Name, FirstName and Title entered before you can save.", "Save Error", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
        '    txtLastName.Focus()
        '    ErrorProviderEmployees.SetError(txtLastName, "")
        '    ErrorProviderEmployees.SetError(txtFirstName, "")
        '    ErrorProviderEmployees.SetError(txtTitle, "")
        '    Exit Sub
        'End If
 
        '' If txtFirstName.Text.Trim = "" Then
 
        ''ErrorProviderEmployees.SetError(txtFirstName, "You must supply a First Name for the Employee")
        '' MessageBox.Show("You must have a First Name entered before you can save.", "Save Error", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
        '' txtFirstName.Focus()
        '' ErrorProviderEmployees.SetError(txtFirstName, "")
        '' Exit Sub
        '' End If
 
        ''If txtTitle.Text.Trim = "" Then
 
        ''ErrorProviderEmployees.SetError(txtTitle, "You must supply a Title for the Employee")
        '' MessageBox.Show("You must have a Title entered before you can save.", "Save Error", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
        ''  txtTitle.Focus()
        ''ErrorProviderEmployees.SetError(txtTitle, "")
        ''Exit Sub
        '' End If
 
        'Dim SavedItem As String = TxtEmployeeID.Text
        'Dim SavedRow As Integer
        'EmployeeIDManager.EndCurrentEdit()
        'EmployeeIDTable.DefaultView.Sort = "LastName"
        '' EmployeeIDTable.DefaultView.Sort = "FirstName"
        ''EmployeeIDTable.DefaultView.Sort = "Title"
        'SavedRow = EmployeeIDTable.DefaultView.Find(SavedItem)
        'EmployeeIDManager.Position = SavedRow
 
        ''Me.ComboBox3.SelectedIndex = EmployeeIDManager.Position
 
 
        'Call ShowUnbound()
        'Call SetState("View")
        'Call controltabs()
    End Sub
 
    Private Sub btnCancel_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCancel.Click
1:      EmployeeIDManager.CancelCurrentEdit()
2:      If MyState = "Add" Then
3:          EmployeeIDManager.Position = MyBookmark
4:          Me.EmployeeIDTable.RejectChanges()
5:          EmployeeRowPosition = 0
6:          EmployeeIDManager.Position = 0
7:      End If
8:      Call ShowUnbound()
9:      Call SetState("View")
10:     TabControl1.SelectedTab = TabPage1
11:     Call controltabs()
    End Sub
 
    Private Sub btnLoadPhoto_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnLoadPhoto.Click
1:      Try
2:          If dlgOpen.ShowDialog = Windows.Forms.DialogResult.OK Then
3:              lblPhotoFileBefore.Text = dlgOpen.FileName
 
4:              Call ShowPhoto()
5:          End If
 
 
6:      Catch ex As Exception
7:          MessageBox.Show(ex.Message, "Error Opening Photo", MessageBoxButtons.OK, MessageBoxIcon.Error)
8:      End Try
    End Sub
 
    Private Sub btnAdd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnAdd.Click
1:      Call SetState("Add")
 
        'ComboBox3.Text = ""
 
2:      MyBookmark = EmployeeIDManager.Position
 
3:      EmployeeIDManager.AddNew()
 
4:      Photo.Image = Nothing
5:      lblPhotoFileBefore.Text = ""
 
6:      lblPhoto.Text = ""
 
        'Call controltabs()
    End Sub
 
    Private Sub btnDelete_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDelete.Click
 
1:      If MessageBox.Show("Are you sure you want to delete this record?", "Delete", MessageBoxButtons.YesNo, MessageBoxIcon.Question, MessageBoxDefaultButton.Button2) = Windows.Forms.DialogResult.Yes Then
2:          Me.Delete()
            'EmployeeIDManager.RemoveAt(EmployeeIDManager.Position)
            ''btnSave.PerformClick()
            'Me.Save()
            ''Call ShowUnbound()
3:      End If
        'Call SetState("View")
        'Call controltabs()
 
    End Sub
 
    Private Sub txtFirstName_KeyPress(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles txtFirstName.KeyPress
1:      If e.KeyChar = ControlChars.Cr Then
2:          txtLastName.Focus()
3:      End If
    End Sub
 
 
    Private Sub btnPrint_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnPrint.Click
        'Declare the document
1:      Dim EmployeeIDDocument As Drawing.Printing.PrintDocument
        'Create the document and name it
2:      EmployeeIDDocument = New Drawing.Printing.PrintDocument()
3:      EmployeeIDDocument.DocumentName = "EmployeeID"
        'Add code handler
        'AddHandler EmployeeIDDocument.PrintPage, AddressOf Me.Print employeeID
        'Print document in preview control
4:      Dim SavedPosition As Integer = EmployeeIDManager.Position
5:      dlgPreview.Document = EmployeeIDDocument
6:      dlgPreview.ShowDialog()
        'Dispose of document when done printing
7:      EmployeeIDDocument.Dispose()
8:      EmployeeIDManager.Position = SavedPosition
    End Sub
 
    Private Sub PrintEmployeeID(ByVal sender As Object, ByVal e As Drawing.Printing.PrintPageEventArgs)
        'draw border
1:      On Error Resume Next 'this just handles the pic box not having an image.
        'no reason not to load it even if it doesn't have a picture lots of work to do here to get this to look clean.
2:      Dim MyPen As Pen = New Pen(Color.Black, 3)
3:      e.Graphics.DrawRectangle(MyPen, e.MarginBounds.X, e.MarginBounds.Y, 300, 350)
4:      Dim MyFont As Font = New Font("Arial", 12, FontStyle.Bold)
5:      Dim S As String = "Employee Data"
6:      Dim SSize As SizeF = e.Graphics.MeasureString(S, MyFont)
7:      e.Graphics.DrawString(S, MyFont, Brushes.Black, e.MarginBounds.X + CInt(0.5 * (300 - SSize.Width)), e.MarginBounds.Y + 15)
        'position picture
8:      e.Graphics.DrawImage(Photo.Image, e.MarginBounds.X + 25, e.MarginBounds.Y + 50, 200, 300)
9:      e.HasMorePages = False
        'first/last name/grade
10:     MyFont = New Font("Arial", 14)
11:     Dim Y As Integer = e.MarginBounds.Y + 260
12:     S = txtFirstName.Text
 
13:     SSize = e.Graphics.MeasureString(S, MyFont)
14:     e.Graphics.DrawString(S, MyFont, Brushes.Black, e.MarginBounds.X + CInt(0.5 * (300 - SSize.Width)), Y)
15:     Y += CInt(MyFont.GetHeight(e.Graphics))
16:     S = txtLastName.Text
17:     SSize = e.Graphics.MeasureString(S, MyFont)
18:     e.Graphics.DrawString(S, MyFont, Brushes.Black, e.MarginBounds.X + CInt(0.5 * (300 - SSize.Width)), Y)
19:     Y += CInt(MyFont.GetHeight(e.Graphics))
20:     S = "Photo " + txtAddress.Text
21:     SSize = e.Graphics.MeasureString(S, MyFont)
22:     e.Graphics.DrawString(S, MyFont, Brushes.Black, e.MarginBounds.X + CInt(0.5 * (300 - SSize.Width)), Y)
    End Sub
 
    Private Sub btnExit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnExit.Click
 
1:      Me.Close()
    End Sub
 
    Private Sub ShowUnbound()
1:      Call ShowPhoto()
2:      txtStatus.Text = (Me.EmployeeIDManager.Position + 1).ToString & " of " & EmployeeIDManager.Count.ToString
    End Sub
 
    Private Sub rdoSex_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles RBMale.CheckedChanged, RBFemale.CheckedChanged
1:      Dim ButtonChecked As RadioButton = CType(sender, RadioButton)
2:      If ButtonChecked.Text = "M" Then
3:          RBMale.Text = "M"
4:      Else
5:          If ButtonChecked.Text = "F" Then
6:              RBFemale.Text = "F"
7:          End If
8:      End If
    End Sub
 
 
    Private Sub BtnLoadPhotoAfter_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)
1:      Try
2:          If dlgOpen.ShowDialog = Windows.Forms.DialogResult.OK Then
3:              lblPhoto.Text = dlgOpen.FileName
4:              Call ShowPhoto()
5:          End If
6:      Catch ex As Exception
7:          MessageBox.Show(ex.Message, "Error Opening Photo", MessageBoxButtons.OK, MessageBoxIcon.Error)
8:      End Try
    End Sub
 
    Private Sub BTNClosePhotoBefore_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
1:      lblPhotoFileBefore.Text = ""
2:      Photo.Image = Nothing 'yes this seems to work
    End Sub
 
 
 
 
 
    Private Sub ComboBox3_SelectedValueChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles ComboBox3.SelectedValueChanged
1:      Me.FillEmployees()
    End Sub
  
 
 
 
    Private Sub controltabs()
1:      If TabControl1.SelectedTab Is TabPage1 Then
2:          btnFirst.Enabled = True
3:          btnNext.Enabled = True
4:          btnPrevious.Enabled = True
5:          btnLast.Enabled = True
            'btnAdd.Enabled = True
6:          btnDelete.Enabled = True
7:          ComboBox3.Enabled = True
 
8:      End If
 
9:      If TabControl1.SelectedTab Is TabPage2 Then
10:         btnFirst.Enabled = False
11:         btnNext.Enabled = False
12:         btnPrevious.Enabled = False
13:         btnLast.Enabled = False
14:         btnAdd.Enabled = False
15:         btnDelete.Enabled = False
16:         ComboBox3.Enabled = False
17:     End If
 
18:     If TabControl1.SelectedTab Is TabPage6 Then
19:         btnFirst.Enabled = False
20:         btnNext.Enabled = False
21:         btnPrevious.Enabled = False
22:         btnLast.Enabled = False
23:         btnAdd.Enabled = False
24:         btnDelete.Enabled = False
25:         ComboBox3.Enabled = False
26:     End If
 
    End Sub
 
    Private Sub TabControl1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles TabControl1.Click
 
1:      Try
2:          If TabControl1.SelectedTab Is TabPage1 Then
3:              btnFirst.Enabled = True
4:              btnNext.Enabled = True
5:              btnPrevious.Enabled = True
6:              btnLast.Enabled = True
7:              btnAdd.Enabled = True
8:              btnDelete.Enabled = True
9:              ComboBox3.Enabled = True
 
10:         End If
11:         If TabControl1.SelectedTab Is TabPage2 Then
12:             btnFirst.Enabled = False
13:             btnNext.Enabled = False
14:             btnPrevious.Enabled = False
15:             btnLast.Enabled = False
16:             btnAdd.Enabled = False
17:             btnDelete.Enabled = False
18:             ComboBox3.Enabled = False
 
19:         End If
 
 
20:         If TabControl1.SelectedTab Is TabPage6 Then
21:             btnFirst.Enabled = False
22:             btnNext.Enabled = False
23:             btnPrevious.Enabled = False
24:             btnLast.Enabled = False
25:             btnAdd.Enabled = False
26:             btnDelete.Enabled = False
27:             ComboBox3.Enabled = False
 
28:         End If
29:     Catch ex As Exception
30:         System.Windows.Forms.MessageBox.Show(ex.ToString)
31:     End Try
    End Sub
 
 
 
 
 
    Private Sub dgEmp_DataError(ByVal sender As System.Object, ByVal e As System.Windows.Forms.DataGridViewDataErrorEventArgs) Handles dgEmp.DataError
1:      Console.WriteLine(e.Exception.ToString)
    End Sub
 
 
 
End Class

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0
 
LVL 18

Expert Comment

by:jcoehoorn
ID: 20384537
Because the concatentation is done by the sql server, not the local machine.  sql server needs the + syntax.
0
 
LVL 18

Expert Comment

by:jcoehoorn
ID: 20384548
Also: I learned the & syntax first, but lately I have been favoring + anyway, because it works with both C# and VB so it's easier to remember if you ever have to move back and forth.
0
 
LVL 1

Author Comment

by:mindserve
ID: 20384981
The backend database is Access, not SQL server, but not sure it that would make a difference. So far I can't seem to find out why the + works but not the & with that particular concatenation string other than I am concatenating fields in the database and not really a string. Although to me it looks like it's a string in the code above ( form load event)
This code works:
Me.EmployeeIDTable.Columns.Add("FullName", GetType(String), "LastName + ', ' + FirstName")



0
 
LVL 18

Accepted Solution

by:
jcoehoorn earned 50 total points
ID: 20385339
I just checked, and to my surprise Access itself does support the & syntax.  It's the only database system I know of that allows it.  Unfortunately, that doesn't explain the problem here.

I can still say this:  it's the database that is doing the concatenation here, not visual basic.  The database is it's own language, and neither knows nor cares anything about how visual basic works.

Hmm, that gives me one other thought:  you're likely going through an OLE connection to talk to access.  It might be that OLE doesn't like the & syntax.
0
 
LVL 1

Author Comment

by:mindserve
ID: 20385531
Yes, OLEDB connection. This is an odd occurance. I just don't want to end up with some code that suddenly doesn't want to concatenate and starts to add, although if it is concatenating the database fields and not a string then it shouldn't be an issue.
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