try
{
SqlConnection sc = new SqlConnection("server=192.1.1.1;uid=sa;pwd=sa;database=kj2006");//连接字符串
SqlDataAdapter sd = new SqlDataAdapter();
DataSet ds = new DataSet();
string str = "SELECT point,address,ssz,dw,sxyj FROM realdata where dw = '"+this.textBox1.Text.Trim()+"' or dw = '"+this.textBox2.Text.Trim()+"' or dw = '"+this.textBox3.Text.Trim()+"' or dw = '"+this.textBox4.Text.Trim()+"' or dw = '"+this.textBox5.Text.Trim()+"'";
sc.Open();
sd.SelectCommand = new SqlCommand(str,sc);
sd.Fill(ds,"realdata");
SqlCommand cmd = sc.CreateCommand();
SqlDataReader dr;
cmd.CommandText ="SELECT point,address,ssz,dw,sxyj FROM realdata where dw = '"+this.textBox1.Text.Trim()+"' or dw = '"+this.textBox2.Text.Trim()+"' or dw = '"+this.textBox3.Text.Trim()+"' or dw = '"+this.textBox4.Text.Trim()+"' or dw = '"+this.textBox5.Text.Trim()+"'";
dr = cmd.ExecuteReader();
if (dr.HasRows)
{
if(dr.GetDouble(2)>dr.GetDouble(4) || dr.GetDouble(2)==dr.GetDouble(4))
{
int i = 0; StreamWriter sw=new StreamWriter(path1,false,Encoding.GetEncoding("gb2312"));
while (dr.Read())
{
i++;
sw.Write(dr.GetString(0).ToString().TrimEnd()+" ");
sw.Write(dr.GetString(1).ToString().TrimEnd()+" ");
sw.Write(dr.GetString(2).ToString().TrimEnd()+" ");
sw.Write(dr.GetString(3).ToString().TrimEnd()+" ");
sw.Write(dr.GetString(4).ToString().TrimEnd()+" ");
sw.WriteLine("");
}
sw.Close();
dr.Close();
}
}
sc.Close();
}
catch(Exception eorr)
{
MessageBox.Show("错误:"+eorr.Message+" !");
}
出现异常提示:错误:在没有任何数据时进行无效的读取尝试!
数据库字段都是char 类型的
{
SqlConnection sc = new SqlConnection("server=192.1.1.1;uid=sa;pwd=sa;database=kj2006");//连接字符串
SqlDataAdapter sd = new SqlDataAdapter();
DataSet ds = new DataSet();
string str = "SELECT point,address,ssz,dw,sxyj FROM realdata where dw = '"+this.textBox1.Text.Trim()+"' or dw = '"+this.textBox2.Text.Trim()+"' or dw = '"+this.textBox3.Text.Trim()+"' or dw = '"+this.textBox4.Text.Trim()+"' or dw = '"+this.textBox5.Text.Trim()+"'";
sc.Open();
sd.SelectCommand = new SqlCommand(str,sc);
sd.Fill(ds,"realdata");
SqlCommand cmd = sc.CreateCommand();
SqlDataReader dr;
cmd.CommandText ="SELECT point,address,ssz,dw,sxyj FROM realdata where dw = '"+this.textBox1.Text.Trim()+"' or dw = '"+this.textBox2.Text.Trim()+"' or dw = '"+this.textBox3.Text.Trim()+"' or dw = '"+this.textBox4.Text.Trim()+"' or dw = '"+this.textBox5.Text.Trim()+"'";
dr = cmd.ExecuteReader();
if (dr.HasRows)
{
if(dr.GetDouble(2)>dr.GetDouble(4) || dr.GetDouble(2)==dr.GetDouble(4))
{
int i = 0; StreamWriter sw=new StreamWriter(path1,false,Encoding.GetEncoding("gb2312"));
while (dr.Read())
{
i++;
sw.Write(dr.GetString(0).ToString().TrimEnd()+" ");
sw.Write(dr.GetString(1).ToString().TrimEnd()+" ");
sw.Write(dr.GetString(2).ToString().TrimEnd()+" ");
sw.Write(dr.GetString(3).ToString().TrimEnd()+" ");
sw.Write(dr.GetString(4).ToString().TrimEnd()+" ");
sw.WriteLine("");
}
sw.Close();
dr.Close();
}
}
sc.Close();
}
catch(Exception eorr)
{
MessageBox.Show("错误:"+eorr.Message+" !");
}
出现异常提示:错误:在没有任何数据时进行无效的读取尝试!
数据库字段都是char 类型的
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if(dr.GetDouble(2)>dr.GetDouble(4) || dr.GetDouble(2)==dr.GetDouble(4))
上面这句代码是不是有问题
if(dr.GetDouble(2)>dr.GetDouble(4) || dr.GetDouble(2)==dr.GetDouble(4))
上面这句代码是不是有问题
if(dr.GetDouble(2)>dr.GetDouble(4) || dr.GetDouble(2)==dr.GetDouble(4))
上面这句代码是不是有问题
dr.GetDouble(2)是实时值
dr.GetDouble(4)是上限预警值
这两个要比较
UP,检查下数据库看看有没有记录
设置个断点调试下吧 if(dr.GetDouble(2)>dr.GetDouble(4) || dr.GetDouble(2)==dr.GetDouble(4)) 写的很有创意的啊
GetString(2)都这样了还ToString干吗呢
if (dr.Read()) //首先要读到!!
dr.Read 和 dr.MoveNext
建议你每执行一次就sc.Close() sc.Open()
SqlDataReader 要单独占用一个连接,如果你上个连接没释放,那么下面就读不到数据。另外,要dr.Reader()先读取才行,不然也是读不到数据的。不知道你是哪种情况,仅供参考
把if(dr.GetDouble(2)>dr.GetDouble(4) || dr.GetDouble(2)==dr.GetDouble(4))
移到了if (dr.Read()) 下
可以过去了
又出现新的异常
说 无效转换
是不是就是下面这句有问题啊
if(dr.GetDouble(2)>dr.GetDouble(4) || dr.GetDouble(2)==dr.GetDouble(4))
数据库字段类型都是char
试试这样:
if(Convert.ToDouble(dr[2])>=Convert.ToDouble(dr[4]))