1.sqlcommand.CommandText = "insert into 留言(liuyan) values @liuyan";//SQL语句写法问题2.sqlconn.Open();//打开连接sqlcommand.Parameters.AddWithValue("@liyan", TextBox1.Text);3.sqlcommand.ExecuteNonQuery();//执行SQL语句 4.sqlcommand = null;//这句不需要啦,可以删掉