How to get UPDATE SQL commands working in VB.net and MySQL? - vb.net

Question

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim con As New MySqlConnection("host=localhost; username=root; password=; database=wh_db")
Dim cmd As New MySqlCommand
Dim dr As MySqlDataReader
con.Open()
cmd.Connection = con
cmd.CommandText = " select pass from user where pass ='" & oldpass.Text & "'"
dr = cmd.ExecuteReader
If dr.HasRows Then
cmd.Connection = con
cmd.CommandText = " UPDATE user SET pass ='" & newpass.Text & "' where user = '" & user.Text & "'"
Else
MsgBox("Password is not correct")
End If
End Sub

Answer 1

I've not used MySQL for a while but have a look at this. It should give you some start into what you're after:
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim dr As MySqlDataReader
Using con As New MySqlConnection(yourConnectionString),
cmd As New MySQLCommand("SELECT pass FROM user WHERE pass = #pass", con)
cmd.Parameters.Add("#pass", MySqlDbType.VarChar).Value = oldpass.Text
con.open()
dr = cmd.ExecuteReader
End Using
If dr.HasRows Then
Using con As New MySqlConnection(yourConnectionString),
cmd As New MySQLCommand("UPDATE user SET pass = #pass WHERE user = #user", con)
cmd.Parameters.Add("#pass", MySqlDbType.VarChar).Value = newpass.Text
cmd.Parameters.Add("#user", MySqlDbType.VarChar).Value = user.Text
con.open()
cmd.ExecuteNonQuery()
End Using
Else
MsgBox("Password is not correct")
End If
End Sub
The reason you're not updating is because you haven't told the command to update. I've also implemented Using which I suggest you do and also look at parameters to stop SQL injection.
I've separated both statements into two Using statements as I feel this would be better rather than attempting to reuse the same object for both the SELECT and UPDATE command.