Develop Reference

System.Data.OleDb.OleDbException Require one or more parameters

I' using Visual Studio Enterprise 2015 WPF to do my Project and my database is a ms access file
I'm not sure why I'm having this error Can someone
An unhandled exception of type 'System.Data.OleDb.OleDbException' occurred in System.Data.dll
Additional information: No value given for one or more required parameters.
Here is my Code
OleDbConnection con = new OleDbConnection();
con.ConnectionString = ConfigurationManager.ConnectionStrings["Connection"].ToString();
con.Open();
OleDbCommand cmd = new OleDbCommand();
cmd.CommandText = "select `Name1`,`ID` from `Employee` WHERE `Name1` = Jacob ";
cmd.Connection = con;
OleDbDataReader rd = cmd.ExecuteReader();
grid1.ItemsSource = rd;
I have also tried
OleDbConnection con = new OleDbConnection();
con.ConnectionString = ConfigurationManager.ConnectionStrings["Connection"].ToString();
con.Open();
OleDbCommand cmd = new OleDbCommand();
cmd.CommandText = "select Name1,ID from [Employee] WHERE Name1 = Jacob ";
cmd.Connection = con;
OleDbDataReader rd = cmd.ExecuteReader();
grid1.ItemsSource = rd;
OleDbConnection con = new OleDbConnection();
con.ConnectionString = ConfigurationManager.ConnectionStrings["Connection"].ToString();
con.Open();
OleDbCommand cmd = new OleDbCommand();
cmd.CommandText = "select * from [Employee] WHERE Name1 = Jacob ";
cmd.Connection = con;
OleDbDataReader rd = cmd.ExecuteReader();
grid1.ItemsSource = rd;
But still the same Error
My Connection String
<connectionStrings>
<add name="Connection" connectionString="Provider=Microsoft.ACE.OLEDB.12.0;Data Source=D:\wpfdb.accdb;Persist Security Info=False;"/>

In your command text lines, for example:
> cmd.CommandText = "select `Name1`,`ID` from `Employee` WHERE `Name1` =
> Jacob ";
Jacob needs to be wrapped in quotes, not column and table names:
cmd.CommandText = "select * Employee WHERE Name1 = 'Jacob' ";

Storing multiple values from an SQL select statement

I have an SQL select query that will return multiple values, but I cannot find a way to store/access them. I am using Visual Studio 2015 and an Access database.
Below is my most recent attempt using a data table/grid view.
string now = DateTime.Today.ToString("dd/MM/yyyy");
//Establish and open new database connection.
OleDbConnection con = new OleDbConnection();
con.ConnectionString = ConfigurationManager.ConnectionStrings["MyDatabase32BITConnectionString"].ToString();
con.Open();
OleDbCommand cmd = new OleDbCommand();
OleDbDataAdapter adapter = new OleDbDataAdapter();
DataTable dt = new DataTable();
cmd.CommandText = String.Format ("select Rating from [RATINGS] where Today_Date like #now and Name like #name");
cmd.Parameters.AddWithValue("#now", now);
cmd.Parameters.AddWithValue("#name", name);
cmd.Connection = con;
adapter.SelectCommand = cmd;
adapter.Fill(dt);
con.Close();
testGridView.DataSource = dt;
name is a variable passed into the method. I don't necessarily need it stored in a data table, i just need to be able to access the results individually to average them (array?).
Any advice would be much appreciated

Auto Completing Textbox

I have a textbox in my winform. I want to autocomplete it with mobile number from a customer table. I have written the code but its not auto completing.
string CS = "data source=.; database=BillingSoftware; user id=sa; Password=9495640";
SqlConnection con = new SqlConnection(CS);
con.Open();
SqlCommand cmd = new SqlCommand("SELECT Phone FROM Customers", con);
SqlDataReader rdr = cmd.ExecuteReader();
AutoCompleteStringCollection CustomerPhone = new AutoCompleteStringCollection();
while (rdr.Read())
{
CustomerPhone.Add(rdr.GetString(0));
}
txt_customerPOS.AutoCompleteCustomSource = CustomerPhone;
con.Close();

Check rdr.Read() whether you have data are not?
or call "Phone" column name
or call rdr["Phone"].ToString()

Received values from my SQL query are displayed incorrect in my Listbox

I'm trying to get values out of my database into my Listbox, I currently send all my results into a new object called Results
I want my listbox to show something like this:
Title(1)(enter)
Url(1)(enter)
Title(2)(enter)
Url(2)(enter)
and so on
It currently still gives an error at OleDbDataReader reader = command.ExecuteReader(); but I have no idea why.
This is the exact code
OleDbConnection connection = new OleDbConnection();
connection.ConnectionString = #"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Users\martijn\Dropbox\Proftaak Periode 2 Identity\Database11.accdb;
Persist Security Info=False;";
connection.Open();
OleDbCommand cmd1 = new OleDbCommand();
cmd1.Connection = connection;
cmd1.CommandText = "SELECT ZoekcriteriaID from Zoekcriteria WHERE ZoekCriteria = '" + Convert.ToString(lbzoektermen.SelectedItem) + "';";
OleDbDataReader reader1 = cmd1.ExecuteReader();
if(reader1.Read())
{
resultaatid = Convert.ToInt32(reader1["ZoekcriteriaID"]);
}
OleDbCommand command = new OleDbCommand();
command.Connection = connection;
command.CommandText = "SELECT Titel, Webadress from Resultaat WHERE ZoekriteriaID = '"+ resultaatid +"';";
OleDbDataReader reader = command.ExecuteReader();
lbresultaten.Items.Clear();
List<Results> resultaten = new List<Results>();
while(reader.Read())
{
Results result = new Results();
result.url = Convert.ToString(reader["Webadress"]);
result.titel = Convert.ToString(reader["Webadress"]);
resultaten.Add(result);
}
foreach(Results result in resultaten )
{
lbresultaten.Items.Add(result.titel);
lbresultaten.Items.Add(result.url);
}
I hope someone could help me,
Kind Regards,
Martijn

Your problem probably lays in your where clause:
SELECT ZoekcriteriaID from Zoekcriteria WHERE **ZoekCriteria**
It should be a column name, not a table name.

display individual columns from sql result in asp.net c#

I'm coding a simple application using c# asp.net. I'm getting the averages of columns. How can I get the individual values from the result and display it in a new label (label1, label2, label3....)?
I tried ExecuteScalar().ToString(); but it returns only the first column.
Below is my code:
SqlConnection con;
con = new SqlConnection("Data Source=.\\SQLEXPRESS;AttachDbFilename=|DataDirectory|\\STATDB.MDF;Integrated Security=True;User Instance=True");
SqlCommand com = new SqlCommand();
SqlDataAdapter da = new SqlDataAdapter();
string result = "SELECT AVG(p_tan) AS p_tang, AVG(e_tan) AS e_tang, AVG(p_rel) AS p_reli FROM statistics";
SqlCommand showresult = new SqlCommand(result, con);
con.Open();
Label1.Text = showresult.ExecuteScalar().ToString();
//Label2.Text = p_tang
//Label3.Text = e_tang
//Label4.Text = p_reli
con.Close();
Any help will be appreciated.

Use showresult.ExecuteReader() and then iterate over the row to get the values
SqlDataReader reader=showresult.ExecuteReader();
while (reader.Read())
{
Label1.Text= reader["p_tang"].ToString().Trim();
Label2.Text= reader["e_tang"].ToString().Trim();
Label3.Text= reader["p_reli"].ToString().Trim();
}

ExecuteScalar will only pull one value. You will need do either use a DataReader or DataAdapter to get multiple values from the database.