sql语句字符串拼接的两种方法 SQL Server

            String ProductionProduct = temp.Rows[i][3].ToString().Trim();

                    //StringBuilder Sql2 = new StringBuilder();

                    //Sql2.Append("select top 1 [ProductID] from [Product] where [productname] =");

                    //Sql2.Append("N'" + ProductionProduct + "';");

                    //String sql22 = Sql2.ToString();

                    String sql2 = @"select [ProductID] from [Product] where [productname] =N'"+ ProductionProduct+ "'";

                    List< ProductModel > res2 = db.Database.SqlQuery(sql2).ToList();

                    string ProductID = string.Empty;

                    foreach ( ProductModel productname in res2)

                    {

                        ProductID = String.Format( "{0}" , productname.ProductID);

                    }

将数据库中字段为空的赋值为0

update Material set MaterialTypeID='0' where MaterialTypeID='' or MaterialTypeID is NULL