Question

我正在开发visual studio 2012 c＃... 我将值插入到combox中......我从数据库中取出它们...我想知道如何将一个项目添加到COMBOBOX中...生成下面的代码：

此函数用于填充组合框，其名称取自数据库包含名称和id中的表：

List<Lookup> fillCombo(string query, string column)
    {
        List<Lookup> lookups = new List<Lookup>();
        using (SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["SQLConnectionString"].ConnectionString))
        {
            conn.Open();
            SqlCommand cmd = new SqlCommand(query, conn);
            SqlDataReader reader = cmd.ExecuteReader();
            while (reader.Read())
            {
                Lookup lookupobject = new Lookup();
                lookupobject.ID = Convert.ToInt32(reader["ID"]);
                //if (reader["Name"] != DBNull.Value)
                lookupobject.Name = reader[column].ToString();

                lookups.Add(lookupobject);
            }


            conn.Close();
        }

        return lookups;
    }

然后我按如下方式调用此函数：

lookups = fillCombo("select id,name from LookupDetails where LOOKUPID =  (select id from Lookup where Name = 'users')", "name");

        comboBox2.DataSource = lookups;
        comboBox2.DisplayMember = "name";

Answer 1

设置DataSource属性时，无法修改ComboxBox Items集合。

您可以选择修改List<Lookup>，也可以通过迭代List<Lookup>将项目添加到combox中。

以下是使用foreach循环在combobox中添加项目并在comboxbox的0索引处插入项目的选项：

lookups = fillCombo(@"select id,name from LookupDetails where LOOKUPID =  
                     (select id from Lookup where Name = 'users')", "name");

foreach(var obj in lookups)
     comboBox2.Items.Add(obj);

comboBox2.DisplayMember = "Name";
comboBox2.Items.Insert(0, "");

注意：在问题中提到的代码中，SqlDataReader从未关闭，我通过包含using语句对其进行了修改。在SqlDataReader块中写下这些内容时，您不必关闭SqlConnection或using：

List<Lookup> fillCombo(string query, string column)
{
    List<Lookup> lookups = new List<Lookup>();
    string sConstring = ConfigurationManager.ConnectionStrings["SQLConnectionString"].ConnectionString;
    using (SqlConnection conn = new SqlConnection(sConstring))
    using(SqlCommand cmd = new SqlCommand(query, conn))
    {
        conn.Open();
        using(SqlDataReader reader = cmd.ExecuteReader())
        {
           while (reader.Read())
           {
              Lookup lookupobject = new Lookup();
              lookupobject.ID = Convert.ToInt32(reader["ID"]);
              //if (reader["Name"] != DBNull.Value)
              lookupobject.Name = reader[column].ToString();
              lookups.Add(lookupobject);
            }
         }
     }        

    return lookups;
}

插入数据源组合框

1 个答案: