hi guys..i have some problem with my VB program..hope u guys can help me out
in my form, there's 8 textboxes that will display data from the database, 3 button's which is '<<' '>>' and 'DELETE'
explanation on my program
---------------------------------
the ' << ' and ' >> ' button will browse through records from the database...while the "delete" button will delete the record from the database...
i have no problem browsing through the records from the database and no problem deleting the records with those buttons
but there's some minor problem..
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problem 1 - when i click on the 'delete' button to delete a record, the data will still appear in the textboxes when i click on the '<<' and '>>' buttons, although the data in the database already been deleted.
problem 2 (same problem related to problem 1) - when i keep clicking on the 'delete' button to delete all the records, the program will then crash and this error message appear 'Concurrency violation: the DeleteCommand affected 0 of the expected 1 records.'..........how to avoid this??
problem 3 - if the database is empty and i log into the form and click on the '<<' , '>>' buttons, the program will then crash and this error message appear 'There is no row at position 1.' ....how to lock those button's when the database is empty or any other ways??
please show me sample codes or something as i will find it hard to understand if you just explain those logic things etc for me
here's my code....
in my form, there's 8 textboxes that will display data from the database, 3 button's which is '<<' '>>' and 'DELETE'
explanation on my program
---------------------------------
the ' << ' and ' >> ' button will browse through records from the database...while the "delete" button will delete the record from the database...
i have no problem browsing through the records from the database and no problem deleting the records with those buttons
but there's some minor problem..
----------------------------------------
problem 1 - when i click on the 'delete' button to delete a record, the data will still appear in the textboxes when i click on the '<<' and '>>' buttons, although the data in the database already been deleted.
problem 2 (same problem related to problem 1) - when i keep clicking on the 'delete' button to delete all the records, the program will then crash and this error message appear 'Concurrency violation: the DeleteCommand affected 0 of the expected 1 records.'..........how to avoid this??
problem 3 - if the database is empty and i log into the form and click on the '<<' , '>>' buttons, the program will then crash and this error message appear 'There is no row at position 1.' ....how to lock those button's when the database is empty or any other ways??
please show me sample codes or something as i will find it hard to understand if you just explain those logic things etc for me
here's my code....
VB.NET:
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Private Sub frmUser_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
con.ConnectionString = "PROVIDER = Microsoft.Jet.OLEDB.4.0;Data Source = H:\Testing\Project\user.mdb"
con.Open()
sql = "SELECT * FROM Table1"
da = New OleDb.OleDbDataAdapter(sql, con)
da.Fill(ds, "Table1List")
con.Close()
maxrows = ds.Tables("Table1List").Rows.Count
txtName.Text = ds.Tables("Table1List").Rows(0).Item(0)
txtUsername.Text = ds.Tables("Table1List").Rows(0).Item(1)
txtNickname.Text = ds.Tables("Table1List").Rows(0).Item(2)
txtPassword.Text = ds.Tables("Table1List").Rows(0).Item(3)
txtCity.Text = ds.Tables("Table1List").Rows(0).Item(4)
txtAddress.Text = ds.Tables("Table1List").Rows(0).Item(5)
txtTown.Text = ds.Tables("Table1List").Rows(0).Item(6)
txtPostcode.Text = ds.Tables("Table1List").Rows(0).Item(7)
End Sub
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Public Sub navigaterecords(ByVal position As Integer)
txtName.Text= ds.Tables("Table1List").Rows(position).Item(0)
txtUsername.Text = ds.Tables("Table1List").Rows(position).Item(1)
txtNickname.Text = ds.Tables("Table1List").Rows(position).Item(2)
txtPassword.Text = ds.Tables("Table1List").Rows(position).Item(3)
txtCity.Text = ds.Tables("Table1List").Rows(position).Item(4)
txtAddress.Text = ds.Tables("Table1List").Rows(position).Item(5)
txtTown.Text = ds.Tables("Table1List").Rows(position).Item(6)
txtPostcode.Text = ds.Tables("Table1List").Rows(position).Item(7)
End Sub
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Private Sub btnNext_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnNext.Click
If inc <> maxrows - 1 Then
inc = inc + 1
navigaterecords(inc)
Else
MessageBox.Show("No more applications!", "Warning", MessageBoxButtons.OK, MessageBoxIcon.Warning)
End If
End Sub
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Private Sub btnPrevious_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnPrevious.Click
If inc <> 0 Then
inc = inc - 1
navigaterecords(inc)
Else
MessageBox.Show("No more applications!", "Warning", MessageBoxButtons.OK, MessageBoxIcon.Warning)
End If
End Sub
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Private Sub btnDelete_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDelete.Click
con.ConnectionString = "PROVIDER = Microsoft.Jet.OLEDB.4.0;Data Source = H:\Testing\Project\user.mdb"
con.Open()
sql = "SELECT * FROM Table1"
da = New OleDb.OleDbDataAdapter(sql, con)
da.Fill(ds, "Table1List")
con.Close()
maxrows = ds.Tables("Table1List").Rows.Count
Dim cb As New OleDb.OleDbCommandBuilder(da)
Dim intresult As Integer
intresult = MessageBox.Show("Confirm Delete?", "Delete", MessageBoxButtons.YesNo, MessageBoxIcon.Question)
If intresult = Windows.Forms.DialogResult.Yes Then
ds.Tables("Table1List").Rows(inc).Delete()
da.Update(ds, "Table1List")
maxrows = maxrows - 1
inc = 0
navigaterecords(inc)
End If
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