I can't connect to my SQL Server database Using VB.NET - sql-server

Question

Protected Sub login_btn_Click(sender As Object, e As EventArgs) Handles login_btn.Click
Dim connString As String
Dim connection As SqlConnection
Dim command As SqlCommand
Dim sql As String
connString = "Data Source=.\SQLExpress;Initial Catalog=Suivi_Invst;Integrated Security=True"
sql = "select NET_ID, Password from User"
connection = New SqlConnection(connString)
Try
connection.Open()
command = New SqlCommand(sql, connection)
Dim sqlReader As SqlDataReader = command.ExecuteReader()
While sqlReader.Read()
If (Password.Text = sqlReader("Password") And NET_ID.Text = sqlReader("NET_ID")) Then
Response.Redirect("Creation.aspx")
End If
End While
sqlReader.Close()
command.Dispose()
connection.Close()
Catch ex As Exception
MsgBox("Can not open connection ! ")
End Try
End Sub
I always get the msg box saying that connection can noy be established.
I tried to open SQL Server Management Studio at the same time the code running but I didn't anything.

Answer 1

From your exception text:
Incorrect syntax near the keyword 'User'
User is reserved keyword in SQL Server.
Basically not recommended to create table having name equals to reserved keywords, but if you really need this name, you have to surround it with square brackets in your query like this:
select NET_ID, Password from [User]

Answer 2

I from what I can see your connection string looks like it's creating the error you forget to escape the "\" character.
additional you can move code inside try block so that you get specific error code
so to escape you can change the line to become
connString = #"Data Source=.\SQLExpress;Initial Catalog=Suivi_Invst;Integrated Security=True";
OR
connString = "Data Source=.\\SQLExpress;Initial Catalog=Suivi_Invst;Integrated Security=True";
so update your code to become:
Protected Sub login_btn_Click(sender As Object, e As EventArgs) Handles login_btn.Click
Dim connString As String
Dim connection As SqlConnection
Dim command As SqlCommand
Dim sql As String
Try
connString = #"Data Source=.\SQLExpress;Initial Catalog=Suivi_Invst;Integrated Security=True"
//OR USE BELOW
//connString = "Data Source=.\\SQLExpress;Initial Catalog=Suivi_Invst;Integrated Security=True"
sql = "select NET_ID, Password from User"
connection = New SqlConnection(connString)
connection.Open()
command = New SqlCommand(sql, connection)
Dim sqlReader As SqlDataReader = command.ExecuteReader()
While sqlReader.Read()
If (Password.Text = sqlReader("Password") And NET_ID.Text = sqlReader("NET_ID")) Then
Response.Redirect("Creation.aspx")
End If
End While
sqlReader.Close()
command.Dispose()
connection.Close()
Catch ex As Exception
MsgBox("Can not open connection ! ")
End Try
End Sub

Answer 3

Protected Sub login_btn_Click(sender As Object, e As EventArgs) Handles login_btn.Click
Dim connString As String
Dim connection As SqlConnection
Dim command As SqlCommand
Dim sql As String
connString = "Data Source=.\SQLExpress;Initial Catalog=Suivi_Invst;Integrated Security=True"
//Instead of
sql = "select NET_ID, Password from User"
//I used this
sql = "SELECT [NET_ID], [Password] FROM [User] "
And it worked
connection = New SqlConnection(connString)
Try
connection.Open()
command = New SqlCommand(sql, connection)
Dim sqlReader As SqlDataReader = command.ExecuteReader()
While sqlReader.Read()
If (Password.Text = sqlReader("Password") And NET_ID.Text = sqlReader("NET_ID")) Then
Response.Redirect("~/Request/Creation.aspx")
End If
End While
sqlReader.Close()
command.Dispose()
connection.Close()
Catch ex As Exception
MsgBox(ex.Message)
End Try
End Sub
thanks everyone