C# 在CRM 4.0中检索单个Guid

我是新加入

CRM（4.0版）

的，我正在尝试返回基于给定年份的“yearid”指南（该指南也存储在实体中）。到目前为止，我已获得：

    public static Guid GetYearID(string yearName)
    {

        ICrmService service = CrmServiceFactory.GetCrmService();

        // Create the query object.
        QueryExpression query = new QueryExpression("year");
        ColumnSet columns = new ColumnSet();
        columns.AddColumn("yearid");
        query.ColumnSet = columns;       

        FilterExpression filter = new FilterExpression();

        filter.FilterOperator = LogicalOperator.And;
        filter.AddCondition(new ConditionExpression
        {
            AttributeName = "yearName",
            Operator = ConditionOperator.Equal,
            Values = new object[] { yearName}
        });

        query.Criteria = filter;

    } 

但我的问题是：


A） 除此之外，还有什么代码可以实际存储Guid？
B） 使用QueryExpression是最有效的方法吗？

Re:B）使用sql可能更快（我不知道用了多少，甚至是否更快），但我认为在99%的情况下，QueryExpression在性能方面是完全可以接受的

Re:A）你的答案很接近，我已经完成了下面的代码

public static Guid GetYearID(string yearName) 
{
    ICrmService service = CrmServiceFactory.GetCrmService(); 

    // Create the query object. 
    QueryExpression query = new QueryExpression("year"); 

    //No need to ask for the id, it is always returned
    //ColumnSet columns = new ColumnSet(); 
    //columns.AddColumn("yearid");
    //query.ColumnSet = columns;

    FilterExpression filter = new FilterExpression(); 

    filter.FilterOperator = LogicalOperator.And; 
    filter.AddCondition(new ConditionExpression 
    { 
        AttributeName = "yearName", 
        Operator = ConditionOperator.Equal, 
        Values = new object[] { yearName} 
    }); 

    query.Criteria = filter; 

    //We have to use a retrieve multiple here
    //In theory we could get multiple results but we will assume we only ever get one
    BusinessEntityCollection years = service.RetrieveMultiple(query);

    DynamicEntity year = (DynamicEntity)years.BusinessEntities.First();

    return ((Guid)year["yearid"]);
}