在数据库表中插入新值时刷新我的列表框 [英] Refresh my listbox when new value is inserted in db table

问题描述

我创建了一个ListBox，用作DataGridView的控件/过滤器.同样，我还具有插入功能来创建新公司.

现在，当用户创建新公司时，我想更新列表框以包含创建的新公司.

Hi I have created a ListBox that works as a controler/filter for my DataGridView. In the same form I also have a insert function to create a new company.

Now when a user creates a new company I want to update the listbox to contain the new company created.

namespace MyNameSpace
{
    // Creating our Listbox, Datatable and DataGridView for later use
    public partial class CompanyForm : Form
    {
        private ListBox companyList = new ListBox();
        private DataTable dataEmployeesSource = new DataTable();
        private DataGridView dataEmployees = new DataGridView();

        //Connection String
        string cs = ConfigurationManager.ConnectionStrings["MyCS"].ConnectionString;

        // we initialize our methods but dont load them
        public CompanyForm()
        {
            InitializeComponent();

            initDataEmployees();
            initCompanyList();

            companyList.SelectedIndexChanged += listbox1_SelectedIndexChanged;
        }

        // The first DataEmployees method to fill our DataGridView is executed
        private void initDataEmployees()
        {
            const string sql = "Select fname, ename, c.companyName AS companyName FROM dbo.Users u inner join dbo.Company c on c.companyName = u.company;";
            dataEmployeesSource = selectIntoDataTable(sql);
            dataEmployees.DataSource = dataEmployeesSource;
        }

        // Method to fill our CompanyList which later works as a filter for our DataGridView
        private void initCompanyList()
        {
            const string sql = "Select companyName from dbo.Company";
            try
            {
                DataTable dt = selectIntoDataTable(sql);
                companyList.DataSource = dt;
                companyList.ValueMember = "companyName";
            }
            catch (Exception ex)
            {
                MessageBox.Show("There are no companies to display");
            }
        }
        // Filling our DataTable locally to enable fast filtering
        private DataTable selectIntoDataTable(string sql)
        {
            DataTable dt = new DataTable();
            using (SqlConnection con = new SqlConnection(cs))
            {
                try
                {
                    con.Open();
                    using (SqlCommand cmd = new SqlCommand(sql, con))
                    using (SqlDataAdapter a = new SqlDataAdapter(cmd))
                    {
                        a.Fill(dt);
                    }
                }
                catch (Exception ex)
                {
                    Console.WriteLine(ex);
                }
                finally
                {
                    con.Close();
                }
            }
                return dt;
            }
        // Here we show the changed value based on the selected index from our CompanyList
        private void listbox1_SelectedIndexChanged(object sender, EventArgs e)
        {
            DataRowView selectedRow = (DataRowView)companyList.SelectedItem;
            string selectedText = (string)selectedRow.Row["companyName"];
            DataView dv = dataEmployeesSource.DefaultView;
            string filter = string.Format("companyName = '{0}'", selectedText);
            dv.RowFilter = filter;
            dataEmployees.DataSource = dv;
        }
        // Create company, we create a company here and insert it into our dbo.Company table
        private void createCompany_Click_1(object sender, EventArgs e)
        {
            if (textBoxCompanyName.Text == "")
            {
                MessageBox.Show("Vänligen fyll i informationen");
                return;
            }
            using (SqlConnection con = new SqlConnection(cs))
            {
                con.Open();
                SqlCommand cmd = new SqlCommand("insert into dbo.Company (companyName) values(@companyName)", con);
                cmd.Parameters.AddWithValue("@companyName", textBoxCompanyName.Text);
                SqlDataAdapter adapt = new SqlDataAdapter(cmd);
                DataSet ds = new DataSet();
                adapt.Fill(ds);
                con.Close();
                MessageBox.Show("Grattis! Du har skapat ett företag");

            }
        }
    }
}

我尝试过的事情:

我试图在createCompany_Click方法的末尾添加更新.

What I have tried:

I have tried to add updates in the end of the createCompany_Click method

推荐答案

您没有在createCompanyClick处理程序中调用cmd.ExecuteNonQuery().

You''re not calling cmd.ExecuteNonQuery() in your createCompanyClick handler.

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