问题描述：
我们在使用Linq To Entities进行分页查询的时候，如果不小心，可能会出现如标题所示的错误，导致查询分页数据失败。那么原因何在呢？
原因：
原因在于用Linq To Entities默认查询出来的数据顺序是聚集索引的顺序，所以必须要加上排序操作。所以为OrderBy或OrderByDescending加上聚集索引字段名称即可。
如下代码所示：
public List<SYS_OperatorDTO> GetSysOperators(int pageIndex, int pageSize, out int total)
{
var query = from a in Db.Set<SYS_Operator>()
join b in Db.Set<SYS_Department>() on a.DepartmentId equals b.DepartmentId into tempAb
from ttAb in tempAb.DefaultIfEmpty()
join c in Db.Set<SYS_Role>() on a.RoleId equals c.RoleId into tempAc
from ttAc in tempAc.DefaultIfEmpty()
where a.Status == 1
select new SYS_OperatorDTO
{
OpeId = a.OperatorId,
ComId = a.CompanyId,
DepId = a.DepartmentId,
DepName = ttAb == null ? "" : ttAb.DepartmentName,
RolId = a.RoleId,
RolName = ttAc == null ? "" : ttAc.RoleName,
Acc = a.Account,
Pwd = a.Pwd,
PhotoWidth = a.PhotoWidth,
PhotoHeight = a.PhotoHeight,
PhotoPath = a.PhotoPath,
Nickname = a.Nickname,
Realname = a.Realname,
WeChat = a.WeChat,
Microblog = a.Microblog,
Mobile = a.Mobile,
Tel = a.Tel,
QQ = a.QQ,
Email = a.Email,
Address = a.Address,
IsEnable = a.IsEnable,
DtlInfo = a.DtlInfo,
Status = a.Status,
CrtTime = a.CrtTime,
CrtOptId = a.CrtOptId,
ModTime = a.ModTime,
ModOptId = a.ModOptId
};
//数据总记录数
total = query.Count();
//分页数据
var list = query.OrderByDescending(m => m.CrtTime).Skip((pageIndex - 1) * pageSize).Take(pageSize);
return list.ToList();
}
