Expression expected ошибка vba

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• Expression expected error

1. Jun 14th, 2017, 04:53 AM

   
   

   #1

   

   Thread Starter

   
   Junior Member
   

   

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   Expression expected error
   

   Hi,

   I have a source code giving «expression expected» error. A small piece of this code below and whole source code is at the attachment. How can I fix this error? Thanks everybody.

   ————————-
   Private Sub ConnectToSQL()

   Dim con As New SqlConnection
   Dim cmd As New SqlCommand
   Dim Password As String
   Dim Password2 As String
   Dim userName As String

   Try
   If (EXPRESSION EXPECTED)
   ‘change the data source and initial catalog according to your sql server engine and data base
   con.ConnectionString = «Data Source = Localhost; Initial Catalog = hdur750; Integrated Security = True»

   ——————————————

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2. Jun 14th, 2017, 06:42 AM

   
   

   #2

   Re: Expression expected error
   

   An If statement needs an expression that evaluates to true or false an If without any condition is meaningless.

   Could you post the relevant section of code here please, show the If statement in full if you have to — most people (myself included) would rather not download a word document from an unknown source just to read some source code.

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3. Jun 14th, 2017, 07:49 AM

   
   

   #3

   

   Thread Starter

   
   Junior Member
   

   

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   Re: Expression expected error
   

   Thank you for your answer. Here is the code. This is a login code in Visual Basic and SQL database

   Code:

   Imports System.Data
   Imports System.Data.SqlClient
   Public Class giris
   
       Private Sub giris_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
   
       End Sub
   
       'Login Button
       Private Sub btnlogin_Click(sender As System.Object, e As System.EventArgs) Handles btnLogin.Click
   
           ConnectToSQL()
   
       End Sub
   
       'Connect to SQL method
   
       Private Sub ConnectToSQL()
   
           Dim con As New SqlConnection
           Dim cmd As New SqlCommand
           Dim Password As String
           Dim Password2 As String
           Dim userName As String
   
           Try
               If        (EXPRESSION EXPECTED)
                       'change the data source and initial catalog according to your sql server engine and data base
                   con.ConnectionString = "Data Source = Localhost; Initial Catalog = hdur750; Integrated Security = True"
                   con.Open()
   
                   cmd.Connection = con
                   'change the data fields names and table according to your database
                   cmd.CommandText = " SELECT  userid, Password FROM   login WHERE   (userid = '" & txtKullanici.Text & "' ) AND (Password = '" & txtSifre.Text & "')"
   
                   Dim lrd As SqlDataReader = cmd.ExecuteReader()
                   If lrd.HasRows Then
                       While lrd.Read()
   
                           'Do something here
                           Password = lrd("password").ToString()
                           userName = lrd("userid").ToString()
   
                           Password2 = txtKullanici.Text()
   
                           If Password = Password2 And userName = txtKullanici.Text Then
   
                               MessageBox.Show("Logged in successfully as " & userName, "", MessageBoxButtons.OK, MessageBoxIcon.Information
                                           )
                               anasayfa.Show()
                               Me.Hide()
   
                               'Clear all fields
                               txtKullanici.Text = ""
                               txtSifre.Text = ""
   
                           End If
   
                       End While
   
                   Else
                       MessageBox.Show("Username and Password do not match..", "Authentication Failure", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
                       'Clear all fields
                       txtSifre.Text = ""
                       txtKullanici.Text = ""
                   End If
   
               End If
   
           Catch ex As Exception
               MessageBox.Show("Error while connecting to SQL Server." & ex.Message)
   
           Finally
               con.Close() 'Whether there is error or not. Close the connection.
   
           End Try
   
       End Sub
   
       Private Sub txtKullanici_TextChanged(sender As System.Object, e As System.EventArgs) Handles txtKullanici.TextChanged
   
       End Sub
   
       Private Sub txtSifre_TextChanged(sender As System.Object, e As System.EventArgs) Handles txtSifre.TextChanged
   
       End Sub
   
       Private Sub btnClear_Click(sender As System.Object, e As System.EventArgs) Handles btnClear.Click
           'User clicking on cancel button only clears field
           ' and refocus to first field
   
           txtKullanici.Text = ""
           txtSifre.Text = ""
           txtKullanici.Focus()
       End Sub
   
   End Class

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4. Jun 14th, 2017, 08:13 AM

   
   

   #4

   Re: Expression expected error
   

   An If statement is used to make a decision about what code to execute based on checking a condition, if the condition is true then you execute the code, if the condition is false then you would execute the code in the «else» part (if one exists).

   You need to decide what you are trying to do here, under what conditions should you be running the code that follows the If statement? Once you have decided on this bit then writing the code to check if it is met should be easy.

   If there is no decision to make then you don’t need an If statement.

   You have a working example of an If further down in the code you posted «If lrd.HasRows Then» and again with «If Password = Password2 And userName = txtKullanici.Text Then»

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5. Jun 14th, 2017, 08:58 AM

   
   

   #5

   

   Thread Starter

   
   Junior Member
   

   

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   Re: Expression expected error
   

   I copied this code from Internet and changed the name of TextBox, Label, Button, Database ..etc. according to my Project.
   In original source code there is not any expression after «If» where the mistake happens. So I couldn’t find any solution here.

   Thanks for your interest a lot.

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6. Jun 14th, 2017, 09:05 AM

   
   

   #6

   Re: Expression expected error
   

   If there is nothing needed then just delete the If and the matching End If and you should be fine.

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7. Jun 14th, 2017, 09:09 AM

   
   

   #7

   Re: Expression expected error
   

   As you don’t know what it would be used for, it would be best to remove that «If» line, and the matching «End If» (just before the Catch).

   edit: I was too slow!

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8. Jun 16th, 2017, 07:00 AM

   
   

   #8

   Re: Expression expected error
   

   Hi…
   Well the first use of a IF in there i can think of is to check if the Textbox’s controls are empty or not, so here is a sample code:

   Code:

   Private Sub ConnectToSQL()
   
           Dim con As New SqlConnection
           Dim cmd As New SqlCommand
           Dim Password As String
           Dim Password2 As String
           Dim userName As String
   
           Try
               If txtKullanici.Text <> "" And txtSifre.text <> "" Then
   
                   'change the data source and initial catalog according to your sql server engine and data base
                   con.ConnectionString = "Data Source = Localhost; Initial Catalog = hdur750; Integrated Security = True"
                   con.Open()
   
                   cmd.Connection = con
                   'change the data fields names and table according to your database
                   cmd.CommandText = " SELECT  userid, Password FROM   login WHERE   (userid = '" & txtKullanici.Text & "' ) AND (Password = '" & txtSifre.Text & "')"
   
                   Dim lrd As SqlDataReader = cmd.ExecuteReader()
                   If lrd.HasRows Then
                       While lrd.Read()
   
                           'Do something here
                           Password = lrd("password").ToString()
                           userName = lrd("userid").ToString()
   
                           Password2 = txtKullanici.Text()
   
                           If Password = Password2 And userName = txtKullanici.Text Then
   
                               MessageBox.Show("Logged in successfully as " & userName, "", MessageBoxButtons.OK, MessageBoxIcon.Information
                                           )
                               anasayfa.Show()
                               Me.Hide()
   
                               'Clear all fields
                               txtKullanici.Text = ""
                               txtSifre.Text = ""
   
                           End If
   
                       End While
   
                   Else
                       MessageBox.Show("Username and Password do not match..", "Authentication Failure", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
                       'Clear all fields
                       txtSifre.Text = ""
                       txtKullanici.Text = ""
                   End If
   
               End If
   
           Catch ex As Exception
               MessageBox.Show("Error while connecting to SQL Server." & ex.Message)
   
           Finally
               con.Close() 'Whether there is error or not. Close the connection.
   
           End Try
   
       End Sub

   But as refered in the upper coments, if you using a «IF» clause its to validate a condition TRUE, FALSE, EQUAL, Superior, Inferior, Diferent, etc…. so when you looking for help especify what do you want to do.

   https://docs.microsoft.com/en-us/dot…else-statement

   PS: You can also be wanting to check if the database exists, if SQL server is there, explain what you want to do maybe people will be able to help.

   Last edited by Mike Storm; Jun 16th, 2017 at 07:09 AM.

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