Need to find a SPItem without knowing the ID of the item

Question

I have two lists and one event receiver. The event receiver sets a column of the list to a unique identifier (combo of the content type and the item id). In the other list I use query string and the newform to set a field to the very same unique identifier above. I also gather some more info in that newform I want to work with.

How can I query a list without knowing the ID, but I have another unique id to single out from the other items so I can work with it just as SPitem firstitem below so I can find the other fields.

---

Getting my first item to get the unique title:

SPSite currentSite = SPContext.Current.Site;
SPWeb web = currentSite.OpenWeb();

string queryString = Request.QueryString["uniqueID"];
SPList firstList = web.Lists["My First List"];
SPItem firstItem = firstList.Items.GetItemById(Convert.ToInt32(queryString));

this is the unique title I want to query second list with:

string uniqueTitle = firstItem["Title"].ToString();

getting my second list up, ready for action:

SPList secondList = web.Lists["My Second List"];

---

Thanks

---

ANSWER:

// open the second list
SPList secondList = web.Lists["My Second List"];

// Query the second list for the item
SPQuery myQuery = new SPQuery();
myQuery.Query = "<Where><Eq><FieldRef Name = \"Title\"/>" +
"<Value Type = \"Text\">" + uniqueTitle +
"</Value></Eq></Where>";

// Get a collection of the second list items selected by the query and pick the first (0) value as it should only return one!
SPListItemCollection secondlistItemCol = secondList.GetItems(myQuery);
SPListItem secondItem = secondlistItemCol[0];

Answer 1

You will want to use the GetItems command with an SPQuery object. It is not too complex to sort out with the MS code example below.

using System;
using Microsoft.SharePoint;

namespace Test
{
   class ConsoleApp
   {
      static void Main(string[] args)
      {
         using (SPSite site = new SPSite("http://localhost"))
         {
            using (SPWeb web = site.OpenWeb())
            {
               // Build a query.
               SPQuery query = new SPQuery();
               query.Query = string.Concat(
                              "<Where><Eq>",
                                 "<FieldRef Name='Status'/>",
                                 "<Value Type='CHOICE'>Not Started</Value>",
                              "</Eq></Where>",
                              "<OrderBy>",
                                 "<FieldRef Name='DueDate' Ascending='TRUE' />",
                                 "<FieldRef Name=’Priority’ Ascending='TRUE' />", 
                              "</OrderBy>");                    

               query.ViewFields = string.Concat(
                                   "<FieldRef Name='AssignedTo' />",
                                   "<FieldRef Name='LinkTitle' />",
                                   "<FieldRef Name='DueDate' />",
                                   "<FieldRef Name='Priority' />");

               query.ViewFieldsOnly = true; // Fetch only the data that we need.

               // Get data from a list.
               string listUrl = web.ServerRelativeUrl + "/lists/tasks";
               SPList list = web.GetList(listUrl);
               SPListItemCollection items = list.GetItems(query);

               // Print a report header.
               Console.WriteLine("{0,-25}  {1,-20}  {2,-25}  {3}",
                  "Assigned To", "Task", "Due Date", "Priority");

               // Print the details.
               foreach (SPListItem item in items)
               {
                  Console.WriteLine("{0,-25}  {1,-20}  {2,-25}  {3}",
                     item["AssignedTo"], item["LinkTitle"], item["DueDate"], item["Priority"]);
               }
            }
         }
         Console.ReadLine();
      }
   }
}