how to concatenate the dropdownlist value in MySql Querry in Asp.net

hi,
Iam Using asp.net with c# with backend as MYSql,
 
i want to select the table name from dropdownlist but it is giving me error can you correct it where iam missing something. below is code iam using.
 
string select=DropDownList1.SelectedItem.Value;
 
string sql="select * from '" + select+"';
 
MySqlCommand cmd = new MySqlCommand(sql, mycon);