使用 OR 而不是 AND 链接/构建 LINQ 查询

编辑得更清楚。

例如，如果我有这个 IQueryable：

DateTime theDate = new DateTime(2015, 09, 30);

var query = from org in Organisations
            where org.DisableOrganisation == false &&
              org.DisableReports == false
            select new
            {
                OrganisationId = org.OrganisationId
            };

稍后在方法中我想添加一个 OR 到它，例如

// Check to see if the date is the last day of the month.
if (theDate.AddDays(1).Day == 1)
{
    // The following statement introduces an AND but I want to make this an OR.
    query = query.Where(x => x.Frequency == "M");
}

这有效地使我的查询......

var query = from org in Organisations
            where org.DisableOrganisation == false &&
              org.DisableReports == false &&
              org.Frequency == "M"
            select new
            {
                OrganisationId = org.OrganisationId
            };

但我想做到...

var query = from org in Organisations
            where (org.DisableOrganisation == false &&
              org.DisableReports == false) ||
              org.Frequency == "M"
            select new
            {
                OrganisationId = org.OrganisationId
            };

我该如何使其成为 OR 而不是 AND ？

P.S.无法使用 PredicateBuilder，因为它本质上是 LinqKit，它依赖于 EntityFramework (≥ 6.0.2)，我被困在使用 EF 4.3.1

SOLVED:感谢D Stanley（说实话我以前用过这种形式的解决方案，我只是忘记了）。

DateTime theDate = new DateTime(2015, 09, 30);
bool isEndOfMonth = theDate.AddDays(1).Day == 1;

var query = from org in Organisations
            where (org.DisableOrganisation == false &&
              org.DisableReports == false) ||
              (isEndOfMonth &&
               pr.ProfileType == "L" && 
               pr.Frequency == "M")
            select new
            {
                OrganisationId = org.OrganisationId
            };

要用 OR 而不是 AND 组合条件，请使用谓词构建器： http://www.albahari.com/nutshell/predicatebuilder.aspx

predicate = predicate.Or(p => p.Description.Contains (temp));
return dataContext.Products.Where(predicate);