simple issue ? Windows forms ..

Question

Hi

 

When i am trying like this :

 

cmd.CommandText = "select LastName,FirstName,EmailAddress,MobilePhone from contactdetails where LastName = 'gutta' ";  my code executing perfect when i am giving static data like gutta ...

 

BUT 

 

I am getting no error ..  .. ..

 

when i am trying like this ..

cmd.CommandText = "select LastName,FirstName,EmailAddress,MobilePhone from contactdetails where LastName = " + textBox1.Text ; 

 

ERROR IS :

dr = cmd.ExecuteReader();  ------------------> 

Invalid column name 'gutta'.

 

Regards