C# C在获取时出现一些错误
您缺少连接块将connectionString替换为您要连接的任何对象:C# C在获取时出现一些错误,c#,C#,您缺少连接块将connectionString替换为您要连接的任何对象: private void TxtFarmerCode_TextChanged(object sender, EventArgs e) { try { cmd.Open(); cmd = new SqlCommand("Select farmername, from cottonpurchase
private void TxtFarmerCode_TextChanged(object sender, EventArgs e)
{
try
{
cmd.Open();
cmd = new SqlCommand("Select farmername, from cottonpurchase where farmercode=@aa", conn);
cmd.Parameters.Add("@aa", SqlDbType.Int).Value = TxtFarmerCode.Text;
dr = cmd.ExecuteReader();
if (dr.HasRows == false)
{
throw new Exception();
}
if (dr.Read())
{
// textBox1.Text = dr[0].ToString(); Since U r going to give the ID and retrieve in textBox1.
TxtFarmerName.Text = dr[0].ToString();
//textBox3.Text = dr[1].ToString();
//textBox4.Text = dr[2].ToString();
//textBox7.Text = dr[3].ToString();
//dateTimePicker1.Text = dr[4].ToString();
//dateTimePicker2.Text = dr[5].ToString();
//textBox5.Text = dr[6].ToString();
}
}
catch
{
// lblError = "THE GIVEN ID IS UNAVAILABLE";
}
finally
{
conn.Close();
}
旁注。。。永远不要抓住{}我不明白?我想从我的数据库中获取值。你能帮我吗?First cmd没有打开的,所以我很确定你需要使用上面的语句。不能说我相信我刚刚编辑的语句,并从帖子中复制了你的所有代码。请显示实际的错误。你从哪里复制了代码?似乎dr、Conn和cmd没有声明。我认为它是从您的SQL中获取的,看起来不可靠。FROM子句前面的逗号在做什么?另外,现在就开始养成良好的编码习惯。抛出包含有意义数据的异常。不要只使用空白构造函数。当您在现场对程序进行故障排除时,您没有调试器或源代码,而这迟早会发生在您身上,您需要了解有关该问题的信息!
using (SqlConnection conn= new SqlConnection(
connectionString))
{
//You have cmd.Open it should be connection
conn.Open();
cmd = new SqlCommand("Select farmername, from cottonpurchase where farmercode=@aa", conn);
cmd.Parameters.Add("@aa", SqlDbType.Int).Value = TxtFarmerCode.Text;
dr = cmd.ExecuteReader();
if (dr.HasRows == false)
{
throw new Exception();
}
if (dr.Read())
{
// textBox1.Text = dr[0].ToString(); Since U r going to give the ID and retrieve in textBox1.
TxtFarmerName.Text = dr[0].ToString();
//textBox3.Text = dr[1].ToString();
//textBox4.Text = dr[2].ToString();
//textBox7.Text = dr[3].ToString();
//dateTimePicker1.Text = dr[4].ToString();
//dateTimePicker2.Text = dr[5].ToString();
//textBox5.Text = dr[6].ToString();
}
}
catch
{
// lblError = "THE GIVEN ID IS UNAVAILABLE";
}
finally
{
conn.Close();
}
}