C# Linq Where可能存在空引用的条件

因此，我正在使用实体框架转换SQL Server存储过程。我必须做的一个查询涉及到一个表的左连接，该表最终被用在where子句中。PS忽略当前的select，我为了调试目的更改了它

    var union3 = (from o in orgs
                  from uos in accessOrgIds.Where(x => o.Id == x)
                  from sr in secRoles.Where(x => x.Id == secRoleId).DefaultIfEmpty()
                  where (o.StatusId == 1)
                  && (secRoleId == 0 || sr == null ? false : sr.Id == secRoleId)
                  select o);

每当sr从where子句中删除时，union3就会产生一个o集。如何在查询中包含该表，并具有与以下SQL相同的效果

    SELECT
        ISNULL(SR.Id, @securityRoleId),
        O.Id,
        O.Name AS OrganizationName,
        SR.Name AS SecurityRoleName,
        -1 AS IsSelected,
        SR.[Description],
        SR.IsSystem,
        SR.IsOATI,
        ISNULL(SR.StatusId, 1) AS StatusId,
        SR.IsAdmin
    FROM 
        Organizations O WITH (NOLOCK)
        INNER JOIN @userOrganizations UOS ON UOS.OrganizationId = O.Id
        LEFT JOIN SecurityRoles SR WITH (NOLOCK) ON SR.Id = @securityRoleId
    WHERE O.StatusId = 1
    AND (@securityRoleId = 0 OR SR.Id = @securityRoleId)

---

PS-@userOrganizations是存储过程的一个更高级的表，它工作正常

您可以按如下所示进行尝试

var union3 = (from o in orgs
              join uos in userOrganizations on uos.OrganizationId equals o.Id
              join sr in SecurityRoles on o.secRoleId equals sr.Id into gj
              from subsr in gj.DefaultIfEmpty()
              where (o.StatusId == 1)
                  && (o.secRoleId == 0 || sr.Id == o.secRoleId)
                  select o);

---

在这里您可以了解。

您可以按如下所示进行尝试

var union3 = (from o in orgs
              join uos in userOrganizations on uos.OrganizationId equals o.Id
              join sr in SecurityRoles on o.secRoleId equals sr.Id into gj
              from subsr in gj.DefaultIfEmpty()
              where (o.StatusId == 1)
                  && (o.secRoleId == 0 || sr.Id == o.secRoleId)
                  select o);

在这里，你可以找到关于这个问题的答案