I have two databases. The first one is shown via a ListBox, and the second one via a ListView. I want to be able to show some information in the ListView based on the chosen ListBox element, but my code doesn't work.
private void DpListBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
L.InitReadOnly(false, NameF, LastNameF, AgeF, DepartmentF, ProfessionF, SalaryF);
L.InitReadOnly(false, Name4, LastName4, Age4, Department4, Profession4, Salary4);
int counter = 0;
IEnumerable<Employee> critCareEmp;
critCareEmp = L.EmpUpdate(counter, Emp, DpListBox, Ep);
SqlConnection connection = new SqlConnection(connectionString);
SqlDataAdapter adapter = new SqlDataAdapter();
Console.WriteLine(DpListBox.SelectedValue.ToString());
SqlCommand command = new SqlCommand($#"SELECT * FROM Employee WHERE Dep_nt={DpListBox.SelectedValue}", connection);
adapter.SelectCommand = command;
DataTable dataTable1 = new DataTable();
adapter.Fill(dataTable1);
Ep.ItemsSource = dataTable1.DefaultView;
}
It seems that I need DpListBox.SelectedValue to be some kind of string, but it's not.
SqlCommand command = new SqlCommand
($#"SELECT * FROM Employee WHERE Dep_nt="+
DpListBox.SelectedValue.ToString(),
connection);
please use parameterized stored procedure
inline query is such a bad practice
Related
I have a combobox in a wpf form. I would like to bind it to a table in MS SQL server. However each time i run my code i keep on running into errors. Any assistance would be appreciated. Below is my code:
private void OnLoad(object sender, RoutedEventArgs e)
{
FillComboBox();
}
protected void FillComboBox()
{
SqlConnection con = new SqlConnection(cs);
DataSet ds = new DataSet();
try
{
con.Open();
SqlCommand cmd = new SqlCommand("SELECT RegNumber,Make FROM Vehicles GROUP BY RegNumber,Make", con);
SqlDataAdapter da = new SqlDataAdapter();
da.SelectCommand = cmd;
da.Fill(ds);
combovehicle.DisplayMemberPath = "RegNumber";
combovehicle.SelectedValue= "Make";
combovehicle.DataContext = ds.Tables[0];
}
catch(Exception)
{
}
}
}
}
combovehicle.DisplayMemberPath = "RegNumber";
combovehicle.SelectedValue= "Make";
combovehicle.DataContext = ds.Tables[0];
So you told WPF to display using the property Make and RegNumber
but you passed in a DataTable object
DataRow does provide indexer for accessing the property but it does NOT contain those properties. Plus DataTable is not IEnumerable so you can't really use it as data source.
AND most importantly you are doing it all wrong. You should almost never make database call directly in your view and set the data source to the output table. You should do this thru MVVM pattern.
I need a help.
I searched and I tried a lot but I am too bad to make it work on my project by myself.
This is code for button-Seek. I want to make Seek-button to fill textbox by respective data.
private void SeekClick(object sender, EventArgs e)
{
if (TBCusNumber.Text != "")
{
string Number = TBCusNumber.Text;
var Conn = new SqlConnection();
Conn.ConnectionString = ConfigurationManager.ConnectionStrings["WindowsFormsApp1.Properties.Settings.DataBase"].ConnectionString;
var Cmd = new SqlCommand();
Cmd.Connection = Conn;
Cmd.CommandText = "SELECT * FROM CustomerList WHERE CustomerNumber = " + Number;
var DataAdapter = new SqlDataAdapter(Cmd);
DataSet DataSet = new DataSet();
DataAdapter.Fill(DataSet, "CustomerList");
CusView.DataSource = DataSet;
CusView.DataMember = "CustomerList";
}
}
And This is the data table.
This is what happens when I put 3 in the text box and press Seek-button.
So here, I want all text boxes to be filled by the data which I searched.
You will get only one row for the query right?
So give like that,
txtFirstName.Text = DataSet.Tables[0].Rows[0]["FirstName"].ToString();
txtLasttName.Text = DataSet.Tables[0].Rows[0]["LastName"].ToString();
Like this you need to assign the values to the respective text boxes.
There are three problem need to fix.
You forget to open the connection with DB,add Conn.Open(); before you excute sql command.
You need to add parameter to prevention SQL Injection
Please use using it will help you to use external resources to return the memory.
when the DataSet be filled you can get the data then fill in textbox
You can follow like this.
private void SeekClick(object sender, EventArgs e)
{
if (TBCusNumber.Text != "")
{
string Number = TBCusNumber.Text;
using (var Conn = new SqlConnection())
{
Conn.ConnectionString = ConfigurationManager.ConnectionStrings["WindowsFormsApp1.Properties.Settings.DataBase"].ConnectionString;
using (var Cmd = new SqlCommand())
{
Cmd.Connection = Conn;
Cmd.CommandText = "SELECT * FROM CustomerList WHERE CustomerNumber = #Number";
Cmd.Parameters.AddWithValue("#Number", Number);
//You miss to add Conn.Open()
Conn.Open();
using (var DataAdapter = new SqlDataAdapter(Cmd))
{
DataSet DataSet = new DataSet();
DataAdapter.Fill(DataSet, "CustomerList");
CusView.DataSource = DataSet;
CusView.DataMember = "CustomerList";
//when the DataSet be filled you can get the data then fill in textbox
txt_firstName.Text = DataSet.Tables[0].Rows[0]["FirstName"].ToString();
}
}
}
}
}
I have set up a listbox called lboxsupplier, i have also created a data adapter which i then used to populate the supplier listbox. When i run the form the listbox is empty. I want the listbox to populate with supplier ID and company which i will then click on to populate another listbox with products.
Namespace Pennyburn_Greg
{
public partial class FormProcess : Form
{
SqlDataAdapter daSupplier;
DataSet dsPennyburnGreg = new DataSet();
SqlConnection conn;
SqlCommand cmdSupplierDetails;
SqlCommandBuilder cmdBSupplier;
DataRow drSupplier;
String connstr, sqlSupplier;
public FormProcess()
{
InitializeComponent();
}
private void FormProcess_Load(object sender, EventArgs e)
{
connstr = #"Data Source= arlene-pc; Initial Catalog= PennyburnGreg; Integrated Security=True";
//dataAdapter for supplier listbox
sqlSupplier = #"Select* from Supplier";
conn = new SqlConnection(connstr);
cmdSupplierDetails = new SqlCommand(sqlSupplier, conn);
daSupplier = new SqlDataAdapter(cmdSupplierDetails);
daSupplier.FillSchema(dsPennyburnGreg, SchemaType.Source, "Supplier");
}
private void filllboxsupplier(string str)
{
daSupplier.Fill(dsPennyburnGreg, "Supplier");
lboxsupplier.DataSource = dsPennyburnGreg.Tables["Supplier"];
lboxsupplier.DisplayMember = "Company";
lboxsupplier.ValueMember = "SupplierID";
}
}
}
First of all, why are you calling FillSchema, rather should be calling Fill method to get the data, like
daSupplier.Fill(dsPennyburnGreg, "Supplier");
Once you have the dataset filled, then in your FormProcess_Load() you can add the dataset as datasource to the listbox like
lboxsupplier.DataSource = dsPennyburnGreg.Tables["Supplier"]
First thing you need to do is loosely couple your UI and data a little bit. Try this code:
// Returns a DataTable of ALL suppliers
private DataTable GetSuppliers()
{
return GetSuppliers(0);
}
// Returns a DataTable of the given supplier
private DataTable GetSuppliers(int supplierId)
{
using (var connection = new SqlCommand())
{
connection.ConnectionString = #"Data Source= arlene-pc; Initial Catalog= PennyburnGreg; Integrated Security=True";
using (var command = new SqlCommand())
{
connection.Open();
command.CommandType = CommandType.Text;
command.Connection = connection;
if (supplierId == 0)
{
command.commandText = "SELECT * FROM Supplier";
}
else
{
command.commandText = "SELECT * FROM Supplier WHERE SupplierId=#id";
command.Parameters.AddWithValue("#id", supplierId);
}
using (var adapter = new SqlDataAdapter())
{
using (var ds = new DataSet())
{
adapter.SelectCommand = command;
adapter.Fill(ds);
if (ds.Tables.Count > 0)
return ds.Tables[0];
}
}
}
}
return null;
}
And now you can just do this:
lboxsupplier.DataSource = GetSuppliers(int.Parse(lboxsupplier.SelectedValue));
lboxsupplier.DisplayMember = "Company";
lboxsupplier.ValueMember = "SupplierID";
Or if you need all Suppliers, just do this:
lboxsupplier.DataSource = GetSuppliers();
lboxsupplier.DisplayMember = "Company";
lboxsupplier.ValueMember = "SupplierID";
This code will provide some separation. This is still not ideal, but beats what you had.
You're not doing anything with the listbox control in FormProcess_Load, so it will be empty when it first loads. I'm assuming you have lboxsupplier_Click bound to the Click event of lboxsupplier? If so, then you'll need to click on that listbox before it will populate the Dataset (which is a very odd user experience, but if that's truly what you need...). If lboxsupplier_Click isn't an event handler, then you're going to have to manually call it.
If it still isn't populating, then try running your query against the database directly, and make sure that it returns data and has columns named "Company" and "SupplierID"
I'm using Visual Studio 2010 and C# to create a windows form with a combobox that should contain employees initials. I have spent the last few days searching through every solution I can find and I still can not get my combobox to populate.
This is what I've got as of now:
public static void FillComboBox(string Query, System.Windows.Forms.ComboBox LoggedByBox)
{
using (var CONN = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\\Users\\Documents\\Service Request Application\\bin\\Debug\\servicereq1.mdb"))
{
CONN.Open();
DataTable dt = new DataTable();
try
{
OleDbCommand cmd = new OleDbCommand(Query, CONN);
OleDbDataReader myReader = cmd.ExecuteReader();
dt.Load(myReader);
}
catch (OleDbException e)
{
Console.WriteLine(e.ToString());
Console.ReadLine();
return;
}
LoggedByBox.DataSource = dt;
LoggedByBox.ValueMember = "ID";
LoggedByBox.DisplayMember = "Initials";
}
}
Then I call it when the form loads
private void Form1_Load(object sender, EventArgs e)
{
FillComboBox("select ID, Initials from [Fixers and Testers]", LoggedByBox);
}
When I run the program, the combobox is still blank. I'm positive that my column names and table names are correct. Any suggestions?
I finally got my ComboBox filled and I wanted to share what I changed for anyone else who stumbles across this question in their searches. After spending a bit more time searching through other questions and MSDN, I was able to come up with this.
private void LoadComboLogged()
{
AppDomain.CurrentDomain.SetData("DataDirectory",#"\\prod\ServiceRequests");
string strCon = #"Provider=Microsoft.Jet.OLEDB.4.0;DataSource=|DataDirectory|\servicereq1.mdb";
try
{
using (OleDbConnection conn = new OleDbConnection(strCon))
{
conn.Open();
string strSql = "SELECT Initials FROM [Fixers and Testers] WHERE [Status] ='C'";
OleDbDataAdapter adapter = new OleDbDataAdapter(new OleDbCommand(strSql, conn));
DataSet ds = new DataSet();
adapter.Fill(ds);
loggedByComboBox.DataSource = ds.Tables[0];
loggedByComboBox.DisplayMember = "Initials";
loggedByComboBox.ValueMember = "Initials";
}
}
catch (Exception ex)
{
}
}
I also found that I needed to call
LoadComboLogged();
when I initialized my form. Without that line, the ComboBox would only show a blank dropdown list. Hope this helps someone else who runs into this problem.
Passing control to static method causing this issue. Instead of passing control to the method make that method returns the table and within the load method load the control.
SqlConnection con = new SqlConnection("Data Source=RUSH-PC\\RUSH;Initial Catalog=Att;Integrated Security=True");
con.Open();
SqlDataAdapter da = new SqlDataAdapter("select name from userinfo", con);
DataTable dt = new DataTable();
da.Fill(dt);
DataRow dr;
dr = dt.NewRow();
dt.Rows.InsertAt(dr, 1);
comboBox1.DisplayMember = "name";
comboBox1.ValueMember = "name";
comboBox1.DataSource = dt;
con.Close();
This may help you...
Good luck...:-)
Another possible solution would be to query and return a list of strings. Perhaps it may be less efficient, but it's what I used in a recent project of mine. Here's an example that would reside in a method, possibly called GetInitialsFromDatabase():
using(var conn = new MySqlConnection(connectionString)
{
conn.Open();
using(MySqlCommand cmd = new MySqlCommand())
{
cmd.Connection = conn;
cmd.CommandText = "SELECT Initials FROM [Fixers and Testers] WHERE [Status] ='C'";
MySqlDataReader reader = cmd.ExecuteReader();
while(reader.Read())
{
// initials is a List<String> previously defined (Assuming strings)
initials.Add(String.Format("{0}", reader[0]));
}
}
conn.Close();
}
And then return the initials List, and then in your GUI you could say:
comboBox1.DataSource = returnedList;
comboBox1.DropDownStyle = ComboBoxStyle.DropDownList;
I created win forms, and I wanna insert sql commands and get data from database. If I put query directly into code sql commands, everything is ok, if I put query by textbox I have a lot of bugs like:
$exception {"Could not find stored procedure 'select * from uczniowie'."}
System.Exception {System.Data.SqlClient.SqlException }
this {MateuszLab4.connectDB} MateuszLab4.connectDB
question "\"select * from uczniowie\"" string
dataTable {} System.Data.DataTable
sqlDataReader null System.Data.SqlClient.SqlDataReader
sqlCommand {System.Data.SqlClient.SqlCommand} System.Data.SqlClient.SqlCommand
Here is my code:
private void buttonSearch_Click(object sender, EventArgs e)
{
string query = textBoxQuery.Text;
connectDB databaseWin = new connectDB("(localdb)\\v11.0", "Mat");
dataGridViewAdvanced.DataSource = databaseWin.DataDownload(query);
}
When I put into string query sql commands (for example string query = "select * from students" ) everything is working very well. If I replaced with data from textbox sth is wrong. Could you give me some tips guys?
here is my class with datadownloada:
public DataTable DataDownload(string question)
{
DataTable dataTable = new DataTable();
SqlDataReader sqlDataReader;
SqlCommand sqlCommand;
sqlCommand = new SqlCommand(question);
sqlCommand.Connection = this.DBconnection;
sqlDataReader = sqlCommand.ExecuteReader();
dataTable.Load(sqlDataReader);
return dataTable;
}
Try this code.
public DataTable DataDownload(string question)
{
using (var ada = new SqlDataAdapter(question, DBconnection))
{
// Use DataAdapter to fill DataTable
DataTable dt = new DataTable();
ada.Fill(dt);
return dt;
}
}