There is no row at position 0 and System.IndexOutOfRangeException - sql

Question

Error :
An unhandled exception of type 'System.IndexOutOfRangeException'
occurred in System.Data.dll and also showing a :There is no row at
position 0
Dim mycn As New SqlConnection(connection)
Dim DT As New DataTable
mycn.Open()
Dim Adapter As New SqlDataAdapter("SELECT * FROM tblUser where username ='" & txtRet.Text & "'", connection)
Adapter.Fill(DT)
txtUserID.Text = DT.Rows(0)("aid").ToString()
txtFirstName.Text = DT.Rows(0)("fname").ToString()
txtMiddleName.Text = DT.Rows(0)("mi").ToString()
txtLastName.Text = DT.Rows(0)("lname").ToString()
DateOfBirthDateTimePicker.Text = DT.Rows(0)("bday").ToString()
txtAge.Text = DT.Rows(0)("age").ToString()
cmbGender.Text = DT.Rows(0)("gender").ToString()
txtContactNo.Text = DT.Rows(0)("contactno").ToString()
txtEmail.Text = DT.Rows(0)("email").ToString()
txtAddress.Text = DT.Rows(0)("address").ToString()
txtUsernamePS.Text = DT.Rows(0)("username").ToString()
txtPasswordPS.Text = DT.Rows(0)("password").ToString()
rtbSQuestions.Text = DT.Rows(0)("squestion").ToString()
rtbAnswer.Text = DT.Rows(0)("answer").ToString()
Dim bytBLOBData() As Byte = _
DT.Rows(0)("userimage")
Dim stmBLOBData As New MemoryStream(bytBLOBData)
UserPictureBox.Image = Image.FromStream(stmBLOBData)
mycn.Close()

Answer 1

This error indicates that no rows were returned and since you're trying to get the first row (...DT.Rows(0)...) it is throwing the error.
My first suggestion would be to wrap your code in Using statements for all of the objects that implement iDisposable. My second suggestion would be to utilize a parameterized query. My last suggestion would be to check if Rows(0) exists before trying to access it.
Here is a quick example:
'Declare the connection object
Dim con As SqlConnection
'Wrap code in Try/Catch
Try
'Set the connection object to a new instance
con = New SqlConnection(connection)
'Create a new instance of the command object
Using cmd As SqlCommand = New SqlCommand("SELECT * FROM [tblUser] WHERE [username]=#username;", con)
'Parameterize the query
cmd.Parameters.AddWithValue("#username", txtRet.Text)
'Open the connection
con.Open()
'Declare a new adapter to fill the data table
Dim adapter As SqlDataAdapter = New SqlDataAdapter(cmd)
adapter.Fill(DT)
'Close the connection
con.Close()
End Using
Catch ex As Exception
'Display the error
Console.WriteLine(ex.Message)
Finally
'Check if the connection object was initialized
If con IsNot Nothing Then
If con.State = ConnectionState.Open Then
'Close the connection if it was left open(exception thrown)
con.Close()
End If
'Dispose of the connection object
con.Dispose()
End If
End Try
If DT.Rows.Count > 0 Then
txtUserID.Text = DT.Rows(0)("aid").ToString()
txtFirstName.Text = DT.Rows(0)("fname").ToString()
txtMiddleName.Text = DT.Rows(0)("mi").ToString()
txtLastName.Text = DT.Rows(0)("lname").ToString()
DateOfBirthDateTimePicker.Text = DT.Rows(0)("bday").ToString()
txtAge.Text = DT.Rows(0)("age").ToString()
cmbGender.Text = DT.Rows(0)("gender").ToString()
txtContactNo.Text = DT.Rows(0)("contactno").ToString()
txtEmail.Text = DT.Rows(0)("email").ToString()
txtAddress.Text = DT.Rows(0)("address").ToString()
txtUsernamePS.Text = DT.Rows(0)("username").ToString()
txtPasswordPS.Text = DT.Rows(0)("password").ToString()
rtbSQuestions.Text = DT.Rows(0)("squestion").ToString()
rtbAnswer.Text = DT.Rows(0)("answer").ToString()
End If