Never concatenate strings to build a SQL command. It leaves you wide open to accidental or deliberate SQL Injection attack which can destroy your entire database. Always use Parameterized queries instead.
When you concatenate strings, you cause problems because SQL receives commands like:
SELECT * FROM MyTable WHERE StreetAddress = 'Baker's Wood'
The quote the user added terminates the string as far as SQL is concerned and you get problems. But it could be worse. If I come along and type this instead: "x';DROP TABLE MyTable;--" Then SQL receives a very different command:
SELECT * FROM MyTable WHERE StreetAddress = 'x';DROP TABLE MyTable;
Which SQL sees as three separate commands:
SELECT * FROM MyTable WHERE StreetAddress = 'x';
A perfectly valid SELECT
DROP TABLE MyTable;
A perfectly valid "delete the table" command
And everything else is a comment.
So it does: selects any matching rows, deletes the table from the DB, and ignores anything else.
So ALWAYS use parameterized queries! Or be prepared to restore your DB from backup frequently. You do take backups regularly, don't you?
Fix that - throughout your whole app, miss one and your DB is at risk - and you will almost certainly find the problem you are working on has gone as well.
Quote:
I'm not very much familiar with parameterised queries that's why am lost
Basics:
Using con As New SqlConnection(strConnect)
con.Open()
Using cmd As New SqlCommand("SELECT description FROM myTable WHERE ID = @ID", con)
cmd.Parameters.AddWithValue("@ID", idToSearchFor)
Using reader As SqlDataReader = cmd.ExecuteReader()
While reader.Read()
Dim desc As String = DirectCast(reader("description"), String)
Console.WriteLine("ID: {0}" & vbLf & " {1}", idToSearchFor, desc)
End While
End Using
End Using
End Using
For full details Google "Parameterised queries VB" and start reading!