C#与SQL2008的问题
private void dtp日期_ValueChanged(object sender, EventArgs e)
{

dairyLoad();

}
这段代码能正常执行，这个时间触发后能正常返回值

public void dairyLoad()
{
Pub.CC.ExecuteSql("delete dairy1 from dairy1 where dairyname=''");
DateTime dtp= dtp日期.Value;
string rtb = rtb内容.Text, tb = tb标题.Text;
SqlCommand thisCommand = Pub.CC.Conn.CreateCommand();
thisCommand.Parameters.Add("@a1", dtp);
thisCommand.CommandText = "select dairytent from dairy1 where dairytime=@a1";//查中相日期的

object countResult = thisCommand.ExecuteScalar();//返回查果的第一行第一列的
if (countResult != null)
{
countResult = thisCommand.ExecuteScalar();
string neirong = countResult.ToString();
rtb内容.Text = neirong;
thisCommand.Parameters.Add("@a2", dtp);
thisCommand.CommandText = "select dairyname from dairy1 where dairytime=@a2";
object countResult2 = thisCommand.ExecuteScalar();
string biaoti = countResult2.ToString();
tb标题.Text = biaoti;
}

else if(countResult==null)//空新建文本
{
rtb = "";
tb = "";
SqlParameter[] pas = new SqlParameter[] {new SqlParameter("@b1", rtb), new SqlParameter("@b2", tb), new SqlParameter("@b3", dtp) };

Pub.CC.ExecuteSql("insert into dairy1 (dairytent,dairyname,dairytime) values (@b1,@b2,@b3)",pas);//在中建立新的
rtb内容.Text = "";
tb标题.Text="";
}
}

private void tvtime_NodeMouseDoubleClick(object sender, TreeNodeMouseClickEventArgs e)//事件
{

TreeNode tn = this.tvtime.Nodes[0];
TreeNode may = null;
foreach (TreeNode nd in tn.Nodes)//找到根节点
{
if (nd.Name == "2013Y")
{ may = nd; }
}
DateTime dtp=Convert.ToDateTime(e.Node.Text);
string str = e.Node.Text;
SqlCommand thisCommand = Pub.CC.Conn.CreateCommand();

thisCommand.CommandText = ("select dairytent from dairy1 where dairytime LIKE '%"+ str +"%'");

object countResult = thisCommand.ExecuteScalar();
if (countResult != null)
{
countResult = thisCommand.ExecuteScalar();
string neirong = countResult.ToString();
rtb内容.Text = neirong;

thisCommand.CommandText = "select dairyname from dairy1 where dairytime like '%"+ str+"%'";
object countResult2 = thisCommand.ExecuteScalar();
string biaoti = countResult2.ToString();
tb标题.Text = biaoti;
}
else if (countResult == null)
{

rtb内容.Text = "";
tb标题.Text = "";
}
}

?而下面这段代码的 if (countResult != null)这个部分则接受到一直是空值，有哪里不一样啊！！！
{
countResult = thisCommand.ExecuteScalar();
string neirong = countResult.ToString();
rtb内容.Text = neirong;

thisCommand.CommandText = "select dairyname from dairy1 where dairytime like '%"+ str+"%'";
object countResult2 = thisCommand.ExecuteScalar();
string biaoti = countResult2.ToString();
tb标题.Text = biaoti;
}


而且如果我通过别的时间触发DTP日期_valuechanged时间dairyload代码也将读取空值！！！求大神解答啊！

[解决办法]
ExecuteScalar只是返回第一列值，你看看数据库中第一列有值吗
[解决办法]
断点看看执行语句，然后放在库里执行以下，是否有返回值