Queries and the Partner WSDL

When using the query() call with the partner WSDL, consider the following guidelines:

• The queryString parameter is case-insensitive. The API will accept field names in the fieldList using any combination of uppercase and lowercase letters. However, in the QueryResult, the case of field names (both predefined and custom fields) will match exactly the value in the name field of the Field type in the DescribeSObjectResult. It is recommended that you use the proper case when specifying fields in the fieldList.
• For the partner WSDL, the ordering of fields in the QueryResult is determined by the field order in the fieldList, not the field order in the WSDL file.
• The fieldList cannot contain duplicate field names. For example:
  • Invalid (returns an error): "SELECT Firstname, Lastname, Firstname FROM User"
  • Valid: "SELECT Firstname, Lastname FROM User"
• The QueryResult always contains all of the fields specified in the fieldList, even if some of the fields contain no data (null). Although SOAP allows you to omit fields that contain no values in the result set, the API always returns an array containing all fields.
• If you use the partner WSDL, a query that includes ID will return the ID field twice in the SOAP XML response data. Similarly, a query that does not include ID will return a single null ID field in the SOAP XML response data. For example, a query for SELECT ID, FirstName, LastName FROM Contact might return a SOAP XML response with records like:
  <records xsi:type="sf:sObject" xmlns="urn:partner.soap.sforce.com">
      <sf:type>Contact</sf:type>
      <sf:Id>0038000000FrjoBQRW</sf:Id>
      <sf:Id>0038000000FrjoBQRW</sf:Id>
      <sf:FirstName>John</sf:FirstName>
      <sf:LastName>Smith</sf:LastName>
  </records>

  This is expected behavior and something to be aware of if you are accessing the full SOAP XML response data and not using WSC to access the web service response.