I am trying to get a connection from my webapp to a database to get values for a dropdownlist but somehow I always get the same Error at the con.Open. Tells me networkname was not found!
protected void Page_Load(object sender, EventArgs e)
{
if (!this.IsPostBack)
{
string query = "SELECT HobbyId, Hobby, IsSelected FROM Hobbies";
//string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
using (SqlConnection con = new SqlConnection("server=localhost/testserver; database=MyDB.dbo; integrated security=true"))
{
using (SqlCommand cmd = new SqlCommand(query))
{
cmd.CommandType = CommandType.Text;
cmd.Connection = con;
con.Open();
using (SqlDataReader sdr = cmd.ExecuteReader())
{
while (sdr.Read())
{
ListItem item = new ListItem();
item.Text = sdr["Hobby"].ToString();
item.Value = sdr["HobbyId"].ToString();
item.Selected = Convert.ToBoolean(sdr["IsSelected"]);
ddlHobbies.Items.Add(item);
}
}
con.Close();
}
}
ddlHobbies.Items.Insert(0, new ListItem("--Select Hobby--", "0"));
}
}
You need to use a backward slash (\) instead of a forward slash (/): server=localhost/testserver should be server=localhost\testserver.
You can also replace localhost with a simple dot (.): server=.\testserver.
Make sure that your SQL server instance is actually running. You can open SQL server configuration manager to check this.
You will also need to enable at least one network protocol for your instance (e.g. named pipes, TCP/IP or shared memory).
Related
This is the code I'm working with right now, I don't get any errors so I can't pinpoint where it's not working:
private void btnAdd_Click(object sender, EventArgs e)
{
string constring = $"Data Source=(LocalDB)\\MSSQLLocalDB;AttachDbFilename=" +
Directory.GetCurrentDirectory().ToString() + "\\BarcodeDB.mdf;Integrated Security=True";
string query =
"INSERT INTO Products (Barcodes, Name, EDate, Quantity, Price) VALUES (#barcodeValue, #nameValue, #dateValue, #quantityValue, #priceValue) ;";
SqlConnection conDataBase = new SqlConnection(constring);
conDataBase.Open();
using (var cmd = new SqlCommand(query, conDataBase))
{
cmd.Parameters.AddWithValue("#barcodeValue", tbxBar.Text);
cmd.Parameters.AddWithValue("#nameValue", tbxName.Text);
cmd.Parameters.AddWithValue("#dateValue", dateDate.Value.Date);
cmd.Parameters.AddWithValue("#quantityeValue", tbxQua.Text);
cmd.Parameters.AddWithValue("#priceValue", tbxPrice.Text);
}
conDataBase.Close();
}
The code might just be wrongly build or I could be missing some part I'm not sure.
I figured out what was not working, was the connection string. So opening a new question for that.
What i had to do is to open the connection and then execute the command
You're not actually running the command. You need to call ExecuteNonQuery or ExecuteScalar:
using (var cmd = new SqlCommand(query, conDataBase))
{
// set parameters...
cmd.ExecuteNonQuery();
}
is there something wrong with my codes. I already try another codes but the problem is still the same. I've been solving this error for a couple of weeks now, and i can't figure it out how to solve it. And also I already try some another code but the problem is still the same.
I want to save a multiple row from dataGrid to my database.
here's the codes that i use to save a multiple row
private void button1_Click(object sender, EventArgs e)
{
MySqlConnection conString = new MySqlConnection("datasource = localhost; port = 3306; Initial catalog = dbnewsystem; username = root;password = 1234");
MySqlCommand command1 = new MySqlCommand("INSERT INTO purchaseorder (orNo, ProdNo, Quantity, total)" +
"VALUES(#ORNo,#ProductNo,#quantity,#total )", conString);
command1.Parameters.AddWithValue("#ORNo", dataGridView1.Rows.Count);
command1.Parameters.AddWithValue("#ProductNo", dataGridView1.Rows.Count);
command1.Parameters.AddWithValue("#quantity", dataGridView1.Rows.Count);
command1.Parameters.AddWithValue("#total", textBox6.Text);
conString.Open();
command1.ExecuteNonQuery();
command1.Connection = conString;
conString.Close();
command1.CommandType = CommandType.StoredProcedure;
command1.CommandText = "pos_save";
if (command1.ExecuteNonQuery() == 1)
{
MessageBox.Show("saved");
}
else
{
MessageBox.Show("Sorry Nothing to be Update");
}
conString.Close();
}
change sequence
command1.Connection = conString;
command1.ExecuteNonQuery();
You have implemented wrong sequence:
...
conString.Open(); // Connection opened
command1.ExecuteNonQuery(); // Try executing (fail)
command1.Connection = conString; // Connection assigned
Change to
conString.Open(); // Connection opened
command1.Connection = conString; // Connection assigned
command1.ExecuteNonQuery(); // Try executing (fail)
A better design is
// Wrap IDisposable into using
using (MySqlConnection conString = new MySqlConnection("...")) {
conString.Open();
// Make SQL Readable
string sql =
#"INSERT INTO purchaseorder(
orNo,
ProdNo,
Quantity,
total)
VALUES(
#ORNo,
#ProductNo,
#quantity,
#total)";
// Wrap IDisposable into using
using (MySqlCommand command1 = new MySqlCommand(sql, conString)) {
command1.Parameters.AddWithValue("#ORNo", dataGridView1.Rows.Count);
command1.Parameters.AddWithValue("#ProductNo", dataGridView1.Rows.Count);
command1.Parameters.AddWithValue("#quantity", dataGridView1.Rows.Count);
command1.Parameters.AddWithValue("#total", textBox6.Text);
command1.ExecuteNonQuery();
}
}
i have problems filling my checkboxlist from a sql in c#. The list is empty when it have been loaded.
I know it would probably be easier with a connection to web.config, but i have decieded not to have web.config in this project. It would be helpfull if anyone could see what i have done wrong.
This is my code:
string connetionString = "Data Source=[DATA-SOURCE];Initial Catalog=[CATALOG];User ID=[USER-ID];Password=[PASSWORD]";
SqlConnection cnn = new SqlConnection(connetionString);
using (SqlCommand cmd = new SqlCommand())
{
cmd.CommandText = "SELECT ModuleID, ModuleName, InternalName, Active FROM dbo.Zodiac_System_Modules WHERE Active = 1 ORDER BY ModuleName ASC";
cmd.Connection = cnn;
cnn.Open();
using (SqlDataReader sdr = cmd.ExecuteReader())
{
while (sdr.Read())
{
ListItem item = new ListItem();
item.Text = sdr["ModuleName"].ToString();
item.Value = sdr["InternalName"].ToString();
chkModules.Items.Add(item);
}
}
cnn.Close();
}
You Are Missing CommandType This:
cmd.CommandType=CommandType.Text;
I am trying to display some values in textboxes from a database by selecting a site ID from a drop down list. The drop down list is working perfectly and showing the site IDs that are stored in the database. While running this application it shows an error:
Execute Reader requires an open and available Connection. The connection's current state is closed.
Code:
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
LoadOption();
}
}
private void LoadOption()
{
DataTable dt = new DataTable();
SqlConnection con = new SqlConnection(#"connectionString");
using (con)
{
SqlDataAdapter adpt = new SqlDataAdapter("SELECT Site_ID FROM tbl_Survey1", con);
adpt.Fill(dt);
ddlSiteID.DataSource = dt;
ddlSiteID.DataTextField = "Site_ID";
ddlSiteID.DataValueField = "Site_ID";
ddlSiteID.DataBind();
ddlSiteID.Items.Insert(0, new ListItem("--Select ID--", ""));
}
}
protected void ddlSiteID_SelectedIndexChanged(object sender, EventArgs e)
{
SqlConnection con = new SqlConnection(#"connectionString");
string selectID = ddlSiteID.SelectedValue;
SqlCommand cmd = new SqlCommand("SELECT Site_Name,Site_Address FROM tbl_Survey1 where Site_ID=#Site_ID", con);
cmd.Parameters.AddWithValue("#Site_ID", selectID);
cmd.CommandType = CommandType.Text;
using (SqlDataReader rdr = cmd.ExecuteReader())
{
if (rdr.HasRows)
{
rdr.Read();
txtSiteName.Text = rdr.GetString(0);
txtSiteAddress.Text=rdr.GetString(1);
}
}
}
}
Source:
<asp:DropDownList ID="ddlSiteID" runat="server" AutoPostBack="True" OnSelectedIndexChanged="ddlSiteID_SelectedIndexChanged">
</asp:DropDownList>
<asp:TextBox ID="txtSiteName" runat="server"></asp:TextBox>
<asp:TextBox ID="txtSiteAddress" runat="server"></asp:TextBox>
The error explains all. Your connection is closed when you call ExecuteReader. But I suppose that you are asking why?.
You think that, because you have already loaded the dropdown, then you could execute your reader without problems. But, unfortunately, the SqlDataAdapter has its own behavior when working with the connection.
From MSDN SqlDataAdapter.Fill
The Fill method retrieves rows from the data source using the SELECT
statement specified by an associated SelectCommand property. The
connection object associated with the SELECT statement must be valid,
but it does not need to be open. If the connection is closed before
Fill is called, it is opened to retrieve data, then closed. If the
connection is open before Fill is called, it remains open.
So you just need to open the connection in this way
protected void ddlSiteID_SelectedIndexChanged(object sender, EventArgs e)
{
string selectID = ddlSiteID.SelectedValue;
using(SqlConnection con = new SqlConnection(#"connectionString"))
using(SqlCommand cmd = new SqlCommand("SELECT Site_Name,Site_Address FROM tbl_Survey1 where Site_ID=#Site_ID", con))
{
con.Open();
cmd.Parameters.AddWithValue("#Site_ID", selectID);
cmd.CommandType = CommandType.Text;
using (SqlDataReader rdr = cmd.ExecuteReader())
{
....
}
}
}
P.S. Remember to keep always your disposable objects like the connection, command and reader inside an Using block to be sure that they are closed and disposed correctly also in case of exceptions
You're missing in the second method an explicit call to open your connection:
con.Open();
Also, you don't dispose of said connection -- be careful with that. Use usings for anything that implements IDisposable:
protected void ddlSiteID_SelectedIndexChanged(object sender, EventArgs e)
{
using (SqlConnection con = new SqlConnection(#"connectionString"))
{
con.Open();
string selectID = ddlSiteID.SelectedValue;
using (SqlCommand cmd = new SqlCommand("SELECT Site_Name,Site_Address FROM tbl_Survey1 where Site_ID=#Site_ID", con))
{
cmd.Parameters.AddWithValue("#Site_ID", selectID);
cmd.CommandType = CommandType.Text;
using (SqlDataReader rdr = cmd.ExecuteReader())
{
if (rdr.HasRows)
{
rdr.Read();
txtSiteName.Text = rdr.GetString(0);
txtSiteAddress.Text=rdr.GetString(1);
}
}
}
}
}
You should open your connection by calling con.Open() before calling ExecuteReader in ddlSiteID_SelectedIndexChanged method. And don't forget to close it in the end.
This means your code may look like
protected void ddlSiteID_SelectedIndexChanged(object sender, EventArgs e)
{
using(var con = new SqlConnection(#"connectionString"))
{
string selectID = ddlSiteID.SelectedValue;
using (var cmd = new SqlCommand("SELECT Site_Name,Site_Address FROM tbl_Survey1 where Site_ID=#Site_ID", con))
{
cmd.Parameters.AddWithValue("#Site_ID", selectID);
cmd.CommandType = CommandType.Text;
con.Open();
try
{
using (SqlDataReader rdr = cmd.ExecuteReader())
{
if (rdr.HasRows)
{
rdr.Read();
txtSiteName.Text = rdr.GetString(0);
txtSiteAddress.Text=rdr.GetString(1);
}
}
}
finally
{
con.Close();
}
}
}
}
try this In SelectedIndexChanged event of DropDown.
SqlCommand requires Connection to be open
SqlConnection con = new SqlConnection(#"connectionString");
string selectID = ddlSiteID.SelectedValue;
SqlCommand cmd = new SqlCommand("SELECT Site_Name,Site_Address FROM tbl_Survey1 where Site_ID=#Site_ID", con);
cmd.Parameters.AddWithValue("#Site_ID", selectID);
cmd.CommandType = CommandType.Text;
con.open
{
using (SqlDataReader rdr = cmd.ExecuteReader())
{
if (rdr.HasRows)
{
rdr.Read();
txtSiteName.Text = rdr.GetString(0);
txtSiteAddress.Text=rdr.GetString(1);
}
}
}
}
con.close();
Check if your connection is open or not.
if (con != null && con.State == ConnectionState.Closed)
{
con.Open();
}
hallo there
This is a very basic question. I am currently a student and have done ASP.NET with C#.
For our purposes it was required to do work with an access database where connecting to it and adding data etc.was very easy.
My feeling is that access is not used much in the real world and would just like to enquire on the easiest and most correct way of establishing a connection to Microsoft Sql Server Database(Transact sql).
In my case the database is called dbActivities with primary data file being dbActivitiesData.mdf.
OleDbDataConnection conn;
conn = new OleDbConnection = #"Provider=Microsoft.Jet.Oledb.4.0:"
#"Data Source=DataBase.mdb";
conn.Open();
Regards
My feeling is that access is not used much in the real world
Unfortunately Access is still very much used in the real world :-)
As far as the correct way is concerned I would recommend you wrapping the connection into a using block to ensure proper handling:
class Program
{
static void Main()
{
var connectionString = #"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\work\DataBase.mdb";
using (var conn = new OleDbConnection(connectionString))
using (var cmd = conn.CreateCommand())
{
conn.Open();
cmd.CommandText = "SELECT Name FROM Customers";
using (var reader = cmd.ExecuteReader())
{
while (reader.Read())
{
var customerName = reader.GetString(reader.GetOrdinal("Name"));
Console.WriteLine(customerName);
}
}
}
}
}
And as far as Microsoft SQL Server is concerned:
var connectionString = #"Data Source=myServerAddress;Initial Catalog=myDataBase;User Id=myUsername;Password=myPassword;";
using (var conn = new SqlConnection(connectionString))
using (var cmd = conn.CreateCommand())
{
conn.Open();
cmd.CommandText = "SELECT Name FROM Customers";
using (var reader = cmd.ExecuteReader())
{
while (reader.Read())
{
var customerName = reader.GetString(reader.GetOrdinal("Name"));
Console.WriteLine(customerName);
}
}
}
string strSQLCommand;
SqlCommand command;
SqlConnection conn = null;
conn =new SqlConnection("Data Source=serverName\IP;Initial Catalog=dbActivities;UID=User;PWD=Password;Max Pool Size=500;");
strSQLCommand = "Your Command";
command = new SqlCommand(strSQLCommand, conn);
command.ExecuteNonQuery();
conn.Close();