DataSet ds = new DataSet();
ds = MyMeans.getDataSet("select sum(data) from hourdata where elec_classID=1 and datetime between dateadd(dy,-1,getdate()) and dateadd(mi,-1,getdate())");
if (ds.Tables[0].Rows.Count > 0)
{
data_sumday = Convert.ToSingle(ds.Tables[0].Rows[0].ItemArray[0]);
MyMeans.getsqlcom("insert into daydata values(1,1,1,getdate()," + data_sumday + "," + data_sumday + "*0.638)");
}当ds取得的是空值时, Convert.ToSingle(ds.Tables[0].Rows[0].ItemArray[0])就会报错因为是select所以ds.Tables[0].Rows.Count好像永远都等于1该用什么判断条件来防止ds=null时进入条件呢? ds!=null 已试过是不行滴
解决方案 »
- 哪位大神进来帮帮忙啊?(关于C#串口编程的问题)
- 【求教】怎样从string型转化成float型?
- 急。。。。。。asp在Dreamweaver中怎么运行不起来是什么原因
- MyFile.Seek(-1, SeekOrigin.Current) 这句是什么意思?
- dataGridView可以直接绑定DataRow数组吗?
- WindowsForm应用程序中如何嵌入IE c#
- 如何让非Enable=False状态下的RichTextBox不让用户复制到文本
- 如何获取多个checkbox的值判断其是否被选中,然后传入数据库?
- Windows form编程问题
- 那位同仁能给点创意?关于.net竞赛
- 求达人帮忙看道题啦。。。。
- repeater如何实现AJAX无刷新分页?
DataSet ds = new DataSet();
ds = MyMeans.getDataSet("select sum(data) from hourdata where elec_classID=1 and datetime between dateadd(dy,-1,getdate()) and dateadd(mi,-1,getdate())");
if (ds.Tables[0].Rows.Count > 0 && !string.IsNullOrEmpty(ds.Tables[0].Row[0].ItemArray[0] as string)))
{
data_sumday = Convert.ToSingle(ds.Tables[0].Rows[0].ItemArray[0]);
MyMeans.getsqlcom("insert into daydata values(1,1,1,getdate()," + data_sumday + "," + data_sumday + "*0.638)");
}
DataSet ds = new DataSet();
ds = MyMeans.getDataSet("select sum(data) from hourdata where elec_classID=1 and datetime between dateadd(dy,-1,getdate()) and dateadd(mi,-1,getdate())");
if (ds.Tables[0].Rows.Count > 0 &&(!(ds.Tables[0].Rows[0].ItemArray[0] is DBNull)) )
{
data_sumday = Convert.ToSingle(ds.Tables[0].Rows[0].ItemArray[0]);
MyMeans.getsqlcom("insert into daydata values(1,1,1,getdate()," + data_sumday + "," + data_sumday + "*0.638)");
}