生成sql查询以将其传递给查询字符串时出现问题... [英] problem in generating the sql query to pass it to query string...

问题描述

我正在尝试在主页上进行登录，并将其传递给另一个页面的查询字符串..

我在生成查询时出错

我正在使用的逻辑如下..

i am trying to make a login in main page and pass it to a querystring to another page..

i am wrong in generating a query

the logic i am using is as below..

while (dr.Read())
{
   if(proid == String.Empty)
   {
      proid =  dr["ProductID"].ToString(); 
   }
   else
   {
      proid += "," + dr["ProductID"].ToString();
   }
}

当我在另一页上使用request.querystring校准查询时，即Productcatalog.aspx

and when i cal the query with request.querystring on another page i.e Productcatalog.aspx

string query = "Select * from Products where ProductID in ('" + Request.QueryString["ID"].ToString() +"') AND UnitCost < 5000";

但生成的查询如下所示

but the query generated is as below

query	"Select * from Products where ProductID= ',63,64,65' AND UnitCost < 5000"	string

我想将查询生成为

i want to generate the query as

Select * from Products where ProductID in (63,64,65) AND UnitCost < 5000

我必须在while循环中进行哪些更改.生成类似的查询.

what changes i have to make in above while loop. to generate the similar query.

推荐答案

循环的一种方法是

One way to do the loop is

while (dr.Read())
{
   proid = dr["ProductID"].ToString() + ", ";
}
proid.TrimEnd(' ', ',');

在更优雅(更快)的版本中，您可以使用StringBuilder.

In more elegant (and faster) version you could use StringBuilder.

尝试:

Try:

string query = "Select * from Products where ProductID in (''" + Request.QueryString["ID"].ToString().Substring(1) +"'') AND UnitCost < 5000";

问题出在以下语句中:

The problem lies in this statement:

proid += "," + dr["ProductID"].ToString();

您在返回的每个值之前都添加了逗号.子字符串将在第一个逗号之后包含所有内容.

You are putting a comma before every value that is returned. The substring will take everything after the first comma.

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