Like Operator Problem

[incinerator]

I am writing code to search for books where some string is within the book's name

it works fine when i set the search parameter to the whole name of the book but when i use the % sign wildcard no results seem to generate

this is my code :

OleDbConnection myConn = null;
string ConnString = @"Provider=Microsoft.Jet.OLEDB.4.0;User Id=;Password=;Data Source=Library.mdb";
 
myConn = new OleDbConnection(ConnString);
 
string OleDb = "SELECT Nom,Auteur,DateEdition  FROM Livres WHERE Nom Like '%bookname%'";
 
OleDbCommand cmd = new OleDbCommand(OleDb,myConn );
cmd.Parameters.Add("@bookname", txtfind.Text);
 
dt = new DataTable();
OleDbDataAdapter ad = new OleDbDataAdapter(cmd);
ad.Fill(dt);
dgsearchbooks.DataSource = dt; 
 

i know it's something in the sql query i just cant seem to figure it out.

[incinerator]

SOLVED

string OleDb = "SELECT Nom,Auteur,DateEdition FROM Livres WHERE Nom Like '%"+txtfind.Text+"%'";

[Plater]

If that wasn't the solution to it, maybe it could be this:
In MS access you use the * as the wildcard and not the % like SQLServer

[incinerator]

i am Indeed using an ms access database but using the % wildcard sign worked for me , but thanks for your reply, appreciated.

[Christian Binder]

I think, the problem was that you've escaped the parameter and missed the @-sign.

string OleDb = "SELECT Nom,Auteur,DateEdition FROM Livres WHERE Nom Like '%bookname%'";
// ...
cmd.Parameters.Add("@bookname", txtfind.Text);
 

Right:

string OleDb = "SELECT Nom,Auteur,DateEdition FROM Livres WHERE Nom Like '%' + @bookname + '%'";
// ...
cmd.Parameters.Add("@bookname", txtfind.Text);
 

OR (apply the percent-signs on parameter addition)

string OleDb = "SELECT Nom,Auteur,DateEdition FROM Livres WHERE Nom Like @bookname";
// ...
cmd.Parameters.Add("@bookname", "%" + txtfind.Text + "%");
 

[Curtis Rutland]

The last thing you want to do is remove the parameter altogether from your query. That leaves you vulnerable to SQL injection attacks. Always use parameterized queries.