我想做一个分页样式表,但是NeerDinner示例将整个数据提取到PaggingList
类型,并且我有超过10 000行要提取,所以我跳过了那一部分。
所以我想出了这个查询
var r = (from p in db.Prizes
join c in db.Calendars on p.calendar_id equals c.calendar_id
join ch in db.Challenges on c.calendar_id equals ch.calendar_id
join ca in db.ChallengeAnswers on ch.challenge_id equals ca.challenge_id
join cr in db.ChallengeResponses on ca.challenge_answer_id equals cr.challenge_answer_id
where
p.prize_id.Equals(prizeId)
&& ch.day >= p.from_day && ch.day <= p.to_day
&& ca.correct.Equals(true)
&& ch.day.Equals(day)
orderby cr.Subscribers.name
select new PossibleWinner()
{
Name = cr.Subscribers.name,
Email = cr.Subscribers.email,
SubscriberId = cr.subscriber_id,
ChallengeDay = ch.day,
Question = ch.question,
Answer = ca.answer
})
.Skip(size * page)
.Take(size);
问题是,如何在Take
部分之前获得结果总数?
我在考虑:
var t = (from p in db.JK_Prizes
join c in db.JK_Calendars on p.calendar_id equals c.calendar_id
join ch in db.JK_Challenges on c.calendar_id equals ch.calendar_id
join ca in db.JK_ChallengeAnswers on ch.challenge_id equals ca.challenge_id
join cr in db.JK_ChallengeResponses on ca.challenge_answer_id equals cr.challenge_answer_id
where
p.prize_id.Equals(prizeId)
&& ch.day >= p.from_day && ch.day <= p.to_day
&& ca.correct.Equals(true)
&& ch.day.Equals(day)
select cr.subscriber_id)
.Count();
但是这将再次进行查询...
有人建议我如何有效地执行此操作?
答案 0 :(得分:13)
如果你这样查询:
var qry = (from x in y
select x).Count();
... LINQ to SQL将足够聪明,使其成为SELECT COUNT
查询,这可能相当有效(效率将更多地取决于查询中的条件)。底线是计数操作发生在数据库中,而不是LINQ代码中。
答案 1 :(得分:0)
写下我的旧评论:好吧,我在一段时间后面临同样的问题,然后我想出了LINQ to SP =)。创建一个SP并将其放入您的实体并使用它。您可以根据需要编写Sp,例如拉动总记录列。与现在使用wright相比,它更容易,更快速。
答案 2 :(得分:0)
您可以为查询逻辑设置计数,并参见下面的示例:
public int GetTotalCountForAllEmployeesByReportsTo(int? reportsTo, string orderBy = default(string), int startRowIndex = default(int), int maximumRows = default(int))
{
//Validate Input
if (reportsTo.IsEmpty())
return GetTotalCountForAllEmployees(orderBy, startRowIndex, maximumRows);
return _DatabaseContext.Employees.Count(employee => reportsTo == null ? employee.ReportsTo == null : employee.ReportsTo == reportsTo);
}