Solved

How to check username availability?

Posted on 2008-06-17
6
827 Views
Last Modified: 2011-10-03
Hi Guys,
I'm using ASP.net + VB.Net + Access. Please help me to uderstand how to check username availability? Thanks. I have the following code:

Protected Sub submitButton_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles submitButton.Click
        Dim con As New Data.OleDb.OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & Server.MapPath("..\App_data\GLC.mdb"))
        Dim SqlCommand As New Data.OleDb.OleDbCommand
        Dim SqlCommandPro As New Data.OleDb.OleDbCommand
        SqlCommand.CommandText = "INSERT INTO Students ( Username, [Password], SchoolID, LastName, FirstName, Email ) Values ('" + UserName.Text.Replace("'", "_") + "','" + Password.Text.Replace("'", "_") + "','" + DropDownListSchool.SelectedValue + "','" + LastName.Text.Replace("'", "_") + "','" + FirstName.Text.Replace("'", "_") + "','" + Email.Text.Replace("'", "_") + "')"
        SqlCommandPro.CommandText = "INSERT INTO ProgramsStudents (Username, CourseID) Values ('" + UserName.Text.Replace("'", "_") + "','" + DropDownListProgram.SelectedValue + "')"
 
 
 
        If Page.IsValid Then
 
 
            con.Open()
 
            SqlCommand.Connection = con
            SqlCommandPro.Connection = con
 
            SqlCommand.ExecuteNonQuery()
            SqlCommandPro.ExecuteNonQuery()
 
 
            con.Close()
 
        End If
    End Sub

Open in new window

0
Comment
Question by:Robertyue
  • 5
6 Comments
 

Author Comment

by:Robertyue
ID: 21808646
Plus, it says my insert statement is wrong...
0
 

Author Comment

by:Robertyue
ID: 21808889
My bad, the insert function works fine...But i need to know how to check username availability, thanks
0
 
LVL 16

Accepted Solution

by:
GreymanMSC earned 500 total points
ID: 21809022
Check the tables before attempting to update.
Protected Sub submitButton_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles submitButton.Click
    If Page.IsValid Then
       Dim con As New Data.OleDb.OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & Server.MapPath("..\App_data\GLC.mdb"))
 
        'check if name is in table
        Dim sqlCheckStudent As String = "SELECT UserName FROM Students WHERE UserName='" + UserName.Text.Replace("'", "_") + "')"
 
        'insert data into table
        Dim sqlInsertStudent As String = "INSERT INTO Students ( Username, Password, SchoolID, LastName, FirstName, Email ) Values ('" + UserName.Text.Replace("'", "_") + "','" + Password.Text.Replace("'", "_") + "','" + DropDownListSchool.SelectedValue + "','" + LastName.Text.Replace("'", "_") + "','" + FirstName.Text.Replace("'", "_") + "','" + Email.Text.Replace("'", "_") + "')"
 
        'check if courseid is in table for that student
        Dim sqlCheckCourse As String = "SELECT CourseID FROM ProgramsStudents WHERE Username='" + UserName.Text.Replace("'", "_") + "' AND CourseID='" + DropDownListProgram.SelectedValue + "'"
 
        Dim sqlInsertCourse As String = "INSERT INTO ProgramsStudents (Username, CourseID) Values ('" + UserName.Text.Replace("'", "_") + "','" + DropDownListProgram.SelectedValue + "')"
 
        con.Open()
        Dim okayToContinue As Boolean = False
        Dim doCheckStudent As New Data.OleDb.OleDbCommand(sqlCheckStudent, con)
        If IsDBNull(doCheckStudent.ExecuteScalar) Then
            Dim doInsertStudent As New Data.OleDb.OleDbCommand(sqlCheckStudent, con)
            okayToContinue = (0 < doInsertStudent.ExecuteNonQuery())
        Else
            '----------------------------------------
            'The Username is already in the table.
            'Do something here.
            '----------------------------------------
            okayToContinue = False 'or true, depending on the above
        End If
        If okayToContinue Then
            Dim doCheckCourse As New Data.OleDb.OleDbCommand(sqlCheckCourse, con)
            If IsDBNull(doCheckCourse.ExecuteScalar) Then
                Dim doInsertCourse As New Data.OleDb.OleDbCommand(sqlInsertCourse, con)
                doInsertCourse.ExecuteNonQuery()
            End If
        End If
        con.close
    End If
End Sub

Open in new window

0
Active Directory Webinar

We all know we need to protect and secure our privileges, but where to start? Join Experts Exchange and ManageEngine on Tuesday, April 11, 2017 10:00 AM PDT to learn how to track and secure privileged users in Active Directory.

 

Author Comment

by:Robertyue
ID: 21809339
What's okayToContinue for? If the Username is already exist, you cannot insert any data. On the other side, if the username is not in the database, you should be able to excute both insert command. I'm really confued with okayToContinue. Could you please explain a liitle? Thanks
0
 

Author Comment

by:Robertyue
ID: 21809398
No matter what username (not exist in the databse) I entered, it says the user is already exist. Please see my code
 Protected Sub submitButton_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles submitButton.Click
        Dim con As New Data.OleDb.OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & Server.MapPath("..\App_data\GLC.mdb"))
        Dim SqlCommand As New Data.OleDb.OleDbCommand
        Dim SqlCommandPro As New Data.OleDb.OleDbCommand
        Dim sqlCheckStudent As String = "SELECT UserName FROM Students WHERE UserName='" + UserName.Text.Replace("'", "_") + "'"
        SqlCommand.CommandText = "INSERT INTO Students ( Username, [Password], SchoolID, LastName, FirstName, Email ) Values ('" + UserName.Text.Replace("'", "_") + "','" + Password.Text.Replace("'", "_") + "','" + DropDownListSchool.SelectedValue + "','" + LastName.Text.Replace("'", "_") + "','" + FirstName.Text.Replace("'", "_") + "','" + Email.Text.Replace("'", "_") + "')"
        SqlCommandPro.CommandText = "INSERT INTO ProgramsStudents (Username, CourseID) Values ('" + UserName.Text.Replace("'", "_") + "','" + DropDownListProgram.SelectedValue + "')"
 
 
 
        If Page.IsValid Then
            Try
 
 
                con.Open()
 
                Dim okayToContinue As Boolean = False
                Dim doCheckStudent As New Data.OleDb.OleDbCommand(sqlCheckStudent, con)
 
                If IsDBNull(doCheckStudent.ExecuteScalar) Then
 
                    SqlCommand.Connection = con
                    SqlCommandPro.Connection = con
 
                    SqlCommand.ExecuteNonQuery()
                    SqlCommandPro.ExecuteNonQuery()
                Else
                    ErrorMessage2.Text = "The Username is already exist!"
                End If
 
            Catch
                ErrorMessage.Text = "Error retrieving data, please try again later!"
            Finally
                con.Close()
            End Try
        Else
            ErrorMessage.Text = "Please complete everything!"
 
        End If
    End Sub

Open in new window

0
 

Author Comment

by:Robertyue
ID: 21817546
I figured out. Thank you anyway!
Protected Sub submitButton_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles submitButton.Click
       
 
 
        Dim con As New Data.OleDb.OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & Server.MapPath("..\App_data\GLC.mdb"))
        Dim Counter As String = "SELECT COUNT(Username) FROM STUDENTS WHERE Username=@Username"
 
 
        Dim SqlCommand As String = "INSERT INTO Students ( Username, [Password], SchoolID, LastName, FirstName, Email ) Values (@Username,@Password,@SchoolID,@LastName,@FirstName,@Email)"
        Dim SqlCommandPro As String = "INSERT INTO ProgramsStudents (Username, CourseID) Values (@Username,@CourseID)"
 
 
 
        If Page.IsValid Then
 
 
            con.Open()
            Dim Count As New Data.OleDb.OleDbCommand(Counter, con)
            Count.Parameters.AddWithValue("@Username", UserName.Text)
 
            Dim CountValue As Integer
            CountValue = CInt(Count.ExecuteScalar())
 
            Dim Mycommand As New Data.OleDb.OleDbCommand(SqlCommand, con)
            Dim Mycommandd As New Data.OleDb.OleDbCommand(SqlCommandPro, con)
 
            Mycommand.Parameters.AddWithValue("@Username", UserName.Text.Replace("'", "_"))
            Mycommand.Parameters.AddWithValue("@Password", Password.Text.Replace("'", "_"))
            Mycommand.Parameters.AddWithValue("@SchoolID", DropDownListSchool.SelectedValue)
            Mycommand.Parameters.AddWithValue("@LastName", LastName.Text.Replace("'", "_"))
            Mycommand.Parameters.AddWithValue("@FirstName", FirstName.Text.Replace("'", "_"))
            Mycommand.Parameters.AddWithValue("@Email", Email.Text.Replace("'", "_"))
 
            Mycommandd.Parameters.AddWithValue("@Username", UserName.Text.Replace("'", "_"))
            Mycommandd.Parameters.AddWithValue("@CourseID", DropDownListProgram.SelectedValue)
 
 
            If CountValue = 0 Then
                Mycommand.ExecuteNonQuery()
                Mycommandd.ExecuteNonQuery()
 
 
            Else : ErrorMessage2.Text = "User Name is Already Exist!"
            End If
            con.Close()
 
 
        End If
 
    End Sub

Open in new window

0

Featured Post

Free Tool: Subnet Calculator

The subnet calculator helps you design networks by taking an IP address and network mask and returning information such as network, broadcast address, and host range.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Sometimes in DotNetNuke module development you want to swap controls within the same module definition.  In doing this DNN (somewhat annoyingly) swaps the Skin and Container definitions to the default admin selections.  To get around this you need t…
User art_snob (http://www.experts-exchange.com/M_6114203.html) encountered strange behavior of Android Web browser on his Mobile Web site. It took a while to find the true cause. It happens so, that the Android Web browser (at least up to OS ver. 2.…
Two types of users will appreciate AOMEI Backupper Pro: 1 - Those with PCIe drives (and haven't found cloning software that works on them). 2 - Those who want a fast clone of their boot drive (no re-boots needed) and it can clone your drive wh…
I've attached the XLSM Excel spreadsheet I used in the video and also text files containing the macros used below. https://filedb.experts-exchange.com/incoming/2017/03_w12/1151775/Permutations.txt https://filedb.experts-exchange.com/incoming/201…

820 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question