作用：c#中用来批量更新数据库
用法：一般和adapter结合使用。
例：
SqlConnection conn = new SqlConnection(strConnection));//连接数据库
SqlDataAdapter myAdapter = new SqlDataAdapter();//new一个adapter对象
adapter.SelectCommand = new SqlCommand("select * from "+strTblName),(SqlConnection) conn); //cmd
SqlCommandBuilder myCommandBuilder = new SqlCommandBuilder(myAdapter); //new 一个 SqlCommandBuilder
myAdapter.InsertCommand = myCommandBuilder .GetInsertCommand();//插入
myAdapter.UpdateCommand = myCommandBuilder .GetUpdateCommand();//更新
myAdapter.DeleteCommand = myCommandBuilder .GetDeleteCommand();//删除
conn.Open();//打开数据库
myAdapter.Update(ds); //更新ds到数据库
conn.Close();//关闭数据库