在绑定数据库中的数据之前将项目添加到组合框 [英] Add an item to combobox before binding data from the database

问题描述

我有一个 Windows 窗体形式的组合框，可以从数据库中检索数据.我做得很好，但我想在数据库中的数据之前添加第一项 <-请选择类别->.我怎样才能做到这一点?我可以把它放在哪里?

I had a combobox in a Windows Forms form which retrieves data from a database. I did this well, but I want to add first item <-Please select Category-> before the data from the database. How can I do that? And where can I put it?

public Category()
{
    InitializeComponent();
    CategoryParent();

}

private void CategoryParent()
{
    using (SqlConnection Con = GetConnection())
    {
        SqlDataAdapter da = new SqlDataAdapter("Select Category.Category, Category.Id from Category", Con);
        DataTable dt = new DataTable();
        da.Fill(dt);
        CBParent.DataSource = dt;
        CBParent.DisplayMember = "Category";
        CBParent.ValueMember = "Id";
    }
}

推荐答案

您可以像这样(首选)将默认文本添加到组合框的 Text 属性中:

You could either add the default text to the Text property of the combobox like this (preferred):

CBParent.Text = "<-Please select Category->";

或者，您可以直接将值添加到数据表中:

Or, you could add the value to the datatable directly:

da.Fill(dt);
DataRow row = dt.NewRow();
row["Category"] = "<-Please select Category->";
dt.Rows.InsertAt(row, 0);
CBParent.DataSource = dt;

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