C# winform： ComboBox 设置下拉框数据源的公共方法

       public static void SetComboList(ComboBox cboSource, string sSQL,string sWindowTxt,string sFirstItem="",DataTable dtSource=null)
       {
           string sError = string.Empty;
           DataTable dt=null;

           if (!string.IsNullOrEmpty(sSQL))
           {
               dt = SqlLiteHelper.GetDataTable(out sError, sSQL);
               if (!string.IsNullOrEmpty(sError))
                   Common.DisplayMsg(sWindowTxt, sError);
           }
           else if (dtSource != null)
           {
               dt = dtSource.Copy();
           }

           if (!string.IsNullOrEmpty(sFirstItem))
           {
               DataRow dr = dt.NewRow();
               dr[0] = -1;
               dr[1] = sFirstItem;

               dt.Rows.InsertAt(dr, 0);
           }

           //cboSource.Items.Clear();

           cboSource.DataSource = dt;
           cboSource.ValueMember = dt.Columns[0].ColumnName;
           cboSource.DisplayMember = dt.Columns[1].ColumnName;
           cboSource.DropDownStyle = ComboBoxStyle.DropDownList;
       }

1, 初始化下拉框数据源 例子：

string sSql = "select id,valuefrom tgExpenditureItem";
Common.SetComboList(cboOutputItem, sSql, this.Text);

或

DataTable dtSource = new DataTable();
dtSource.Columns.Add("id");
dtSource.Columns.Add("value");
dtSource.Rows.Add(1, "aa");
dtSource.Rows.Add(2, "bb");
dtSource.Rows.Add(3,"cc");

Common.SetComboList(cboOutputItem, "", this.Text, "(全部)", dtSource);

2, 取值可以通过

cboOutputItem.SelectedIndex
cboOutputItem.SelectedItem.ToString()
cboOutputItem.SelectedValue 等方式来取

3, SqlLiteHelper 类请参考：

用于sqlite数据库的SqlLiteHelper.cs 的类
http://blog.csdn.net/keenweiwei/article/details/6845687