传值问题

[ZJM2032]

string CatalogId;
string tkeyword;

protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
CatalogId = Request.Params["CatalogId"].ToString(); //未将对象引用设置到对象的实例。

tkeyword = Request.Params["Keyword"].ToString(); //未将对象引用设置到对象的实例。

GetProducts(CatalogId,tkeyword);
}
}


private void GetProducts(string sCatalogId, string skey)
{
string cmdText = "SELECT * FROM Photos ORDER BY Id DESC";
if (sCatalogId != null)
{
cmdText = "SELECT * FROM Photos where CatalogId=" + sCatalogId + " ORDER BY Id DESC";
}
if (skey != null)
{
cmdText = "SELECT * FROM Photos where name like '%" + skey +"%' ORDER BY Id DESC";
}
}

为什么会出现这样的错误，如果两个值都给了的话就能显示，但如果只传了一个的话就会出错
那我想一次只传一个值，要么类别，要么关键字的话要怎么做，后面已经有判断了啊，哪里要改一下？

[xueyuyang]

CatalogId = Request.Params["CatalogId"].ToString(); //未将对象引用设置到对象的实例。

tkeyword = Request.Params["Keyword"].ToString(); //未将对象引用设置到对象的实例。
这里就应该判断。Request.Params["CatalogId"]. Request.Params["Keyword"].这2个参数任何一个为空的话ToString().都是会报错的，空对象如何能执行Tostring（）方法呢？

[angel6709]

问题，哎，太多了。。。。
if(Request.Params["CatalogId"]!=null)
{
CatalogId = Request.Params["CatalogId"].ToString();
}
if (sCatalogId != null)
{
cmdText = "SELECT * FROM Photos where CatalogId=" + sCatalogId + " ORDER BY Id DESC";
}
esle if (skey != null)
{
cmdText = "SELECT * FROM Photos where name like '%" + skey +"%' ORDER BY Id DESC";
}

[朕赐你肥皂]

CatalogId = !String.IsNullOrEmpty(Request.Params["CatalogId"].ToString())?Request.Params["CatalogId"].ToString():String.Empty;
tkeyword = !String.IsNullOrEmpty(Request.Params["Keyword"].ToString())?Request.Params["Keyword"].ToString():String.Empty;

[ZJM2032]

[Quote=引用 2 楼 angel6709 的回复:]
问题，哎，太多了。。。。
if(Request.Params["CatalogId"]!=null)
{
CatalogId = Request.Params["CatalogId"].ToString();
}
        if (sCatalogId != null)
        {
            cmdText = "SELECT * FROM Photos where CatalogId=" + sCatalogId + " ORDER BY Id DESC";
        }
        esle if (skey != null)
        {
            cmdText = "SELECT * FROM Photos where name like '%" + skey +"%' ORDER BY Id DESC";
        }

[/Quote]谢谢啦，我之前也是这么写的，但是没效果，所以我才去掉的

[ZJM2032]

[Quote=引用 3 楼 gaind 的回复:]
CatalogId = !String.IsNullOrEmpty(Request.Params["CatalogId"].ToString())?Request.Params["CatalogId"].ToString():String.Empty;
tkeyword =  !String.IsNullOrEmpty(Request.Params["Keyword"].ToString())?Request.Params["Keyword"].ToString():String.Empty;
[/Quote]

用这个还是有错误啊，一样的//未将对象引用设置到对象的实例

[ysmz555]

private void GetProducts(string sCatalogId, string skey)
{
string cmdText = "SELECT * FROM Photos ORDER BY Id DESC";
if (sCatalogId != null || skey != null)
{
cmdText = "SELECT * FROM Photos where CatalogId=" + sCatalogId + " ORDER BY Id DESC";

cmdText = "SELECT * FROM Photos where name like '%" + skey +"%' ORDER BY Id DESC";
}
}

[ZJM2032]

[Quote=引用 6 楼 ysmz555 的回复:]
private void GetProducts(string sCatalogId, string skey)
    {
        string cmdText = "SELECT * FROM Photos ORDER BY Id DESC";
        if (sCatalogId != null || skey != null)
        {
            cmdText = "SELECT * FROM Photos where CatalogId=" + sCatalogId + " ORDER BY Id DESC";
     
            cmdText = "SELECT * FROM Photos where name like '%" + skey +"%' ORDER BY Id DESC";
        }
    }

[/Quote]

一次写两个cmdtext这样不行的吧？

[ysmz555]

改成两个不同的呢?
private void GetProducts(string sCatalogId, string skey)
{
string cmdText = "SELECT * FROM Photos ORDER BY Id DESC";
string cmdText1 = "SELECT * FROM Photos ORDER BY Id DESC";
if (sCatalogId != null || skey != null)
{
cmdText = "SELECT * FROM Photos where CatalogId=" + sCatalogId + " ORDER BY Id DESC";

cmdText1 = "SELECT * FROM Photos where name like '%" + skey +"%' ORDER BY Id DESC";
}
}
思路大概应这样,对于你这一问题,我没上机测试对不对.

[ZJM2032]

谢谢，我已经换别的办法解决了