如果我的数据表为空值，则条件仍然为true ..告诉我我使用的条件是.... [英] if my datatable is null value still condition true..tell me which condition i use....

问题描述

我的代码

protected void Page_Load(object sender, EventArgs e)
   {
       if (!IsPostBack)
       {
           DataTable dtMax = gen.GetDataTable("SPSelectDCNMForMaxRecord");
           if (dtMax.Rows.Count > 0)
           {
               string strMaxNo = (Convert.ToInt32(dtMax.Rows[0]["maxRecord"].ToString()) + 1).ToString();
               lblDCNO.Text = strMaxNo;
           }
           else
           {
               lblDCNO.Text = "00000000001";
           }
           txtDate.Text =DateTime.Now.ToString();
           fillCustomerName();

           BindGrid();
       }

推荐答案

检查是否存在null:

Check for a null:

DataTable dtMax = gen.GetDataTable("SPSelectDCNMForMaxRecord");
if (dtMax != null && dtMax.Rows.Count > 0)

顺序很重要:如果您不先检查null，您将得到

The order is important: if you don''t check for null first, you will get an exception as you have been.

请在检查行计数之前检查null值.
if(dtMax！= null)

谢谢
Anil

Hi
please check null value before checking the row count.
if(dtMax != null)

Thanks
Anil

您可能还想检查行值是否不为空

You may also want to check the row value isn''t null

// checks the DataTable isn''t null, the maxRecord valus isn''t null and DataTable has rows

if (dtMax != null && dtMax.Rows.Count > 0 && dtMax.Rows[0]["maxRecord"] != null)

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