数据阅读器问题

Question

下午，我正在编写一个数据库管理程序，以方便工作。如果表没有返回结果，我在使用datareader时遇到问题。我已经在网上搜索了一个解决方案，但无济于事。所以我正在吃谦卑的馅饼并问。

首先，您了解数据库布局，我们有多个表，我想在一个列表视图中显示结果。代码适用于显示整个表，但是当尝试搜索时，在第一个表中找不到结果，那么它会为循环中的每个表抛出一个异常。但是如果在第一个表中找到结果，它将继续循环，直到在每个表中找不到搜索字符串。

这是代码

private string _strDBPath;
private string _strContractNumber;
public string[] dbTables = new string[9] {"0", "1800", "2800", "4000", "5000", "5400", "5700", "6800", "7800"};
public string[] dbFields = new string[3] { "ContractNumber", "Name", "REF",};
private enum sqlType {Normal, Search}
private bool dbSearch =false;



private void frmRecords_Load(object sender, EventArgs e)
{
        lstContractsAddColums();
        timerStart.Start();
    }

    private void lstContractsAddColums()
    {
        lstContracts.Columns.Clear();

        for (int i = 0; i < dbFields.Length; i++) //Check to see if last field in array
            lstContracts.Columns.Add(dbFields[i], 200, HorizontalAlignment.Left);
    }

    private void timerStart_Tick(object sender, EventArgs e)
    {
        for (int i = 0; i < dbTables.Length; i++)
        {
            while (!dbSearch == false)
            {

            }
            dbGetData(i, sqlType.Search, "1000", "ContractNumber");
            dbSearch = false;
        }

        timerStart.Stop();
    }

    private void dbGetData(int dbTable, sqlType sqlRecords, string strSearch, string strField)
    {


        string mySQL = "SELECT ";

        for (int i = 0; i < dbFields.Length; i++) //Check to see if last field in array
            if (i < dbFields.Length - 1)
            {
                mySQL = mySQL + dbFields[i] + ", "; //This is not the last field
            }
            else
            {
                mySQL = mySQL + dbFields[i] + " "; //This is the last field (No commor required)
            }

        switch (sqlRecords)
        {
            case sqlType.Normal:
                mySQL = mySQL + " From " + dbTables[dbTable] + " ORDER BY ContractNumber"; //Adds the last part of the sayntex           
            break;

            case sqlType.Search:
                mySQL = mySQL + " From " + dbTables[dbTable] + " WHERE " + strField + " = " + strSearch; //Adds the last part of the sayntex
                break;
            default:
                mySQL = mySQL + " From " + dbTables[dbTable] + " ORDER BY ContractNumber"; //Adds the last part of the sayntex 
                break;
        }

        ConnStr = @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + strDBPath + ";Jet OLEDB:Database Password="; //Selects the database along with the provider of the database

        try 
        {

            using(OleDbConnection MyConn = new OleDbConnection(ConnStr) )
            {
                MyConn.Open(); //opens MyConn 
                OleDbCommand Cmd = new OleDbCommand(mySQL, MyConn);
                OleDbDataReader ObjReader = Cmd.ExecuteReader();

                if (!ObjReader.HasRows)
                {
                    MessageBox.Show("No rows found"); 
                }
                else
                {
                    while (ObjReader.Read())
                    {
                        ListViewItem item = new ListViewItem(ObjReader[dbFields[0].ToString()].ToString());
                        for (int i = 1; i < dbFields.Length; i++) //Check to see if last field in array
                            item.SubItems.Add(ObjReader[dbFields[i]].ToString());
                        lstContracts.Items.Add(item);
                    }  
                }
                dbSearch = true;
                ObjReader.Close();
                Cmd.Dispose();
                MyConn.Close();
            } 
        }
        catch (Exception ex)
        {
            oErrorLog.WriteErrorLog(ex.ToString());
            dbSearch = true;
        }
        finally
        {
            dbSearch = true;
        }
    }

这可能是愚蠢的，但任何建议都可以提供帮助。