C# 组合框默认值

Question

我正在尝试根据选定的项目抛出组合框来创建 SQL 语句。我想选择默认项目作为 ID，但现在它 returns NULL。我做错了什么？

private void Win_Shown(object sender, EventArgs e)
{
   myBox.SelectedValue = "ID";
   myBox.SelectedText = "ID";
   myBox.SelectedItem = "ID";

   myBox.Items.Add("ID");
   myBox.Items.Add("Name");
   myBox.Items.Add("Surname");
   myBox.Items.Add("Mobile"); 
}

然后在for SQL语句中

MySQL.DisplayAndSearch("SELECT * FROM Data WHERE " + this.myBox.SelectedItem.ToString() + " LIKE '%" + txt_Search.Text + "%'", dataGridView1);

感谢您的帮助:)

Answer 1

你试过了吗？

        private void Win_Shown(object sender, EventArgs e)
    {
    
       myBox.Items.Add("ID");
       myBox.Items.Add("Name");
       myBox.Items.Add("Surname");
       myBox.Items.Add("Mobile"); 

// now select it
            myBox.SelectedIndex = myBox.FindString("Mobile");//id..etc
    }

Answer 2

您在插入前选择项目：

private void Win_Shown(object sender, EventArgs e)
{
   // first, add the items   
   myBox.Items.Add("ID");
   myBox.Items.Add("Name");
   myBox.Items.Add("Surname");
   myBox.Items.Add("Mobile"); 

   // now select it
   myBox.SelectedItem = "ID";
}

C# 组合框默认值

C# Combo box default value

c#

sql

combobox

visual-studio