EntityFramework 根据时间筛选数据

需求：根据当前时间，获取条件合适的数据，其中截止时间只比较日期。

1. 运行会报错的版本：

var lifeWorkEventBatch = clientRepositoryContainer.LifeWorkEventBatchRepository.FindAll(lfe => lfe.SelectionStartTime <= DateTime.Now && lfe.SelectionEndTime >= DateTime.Now.Date).FirstOrDefault();

这里查资料得知：sql里面没有根据当前日期再获取Date的函数，因此不能转换成功，直接报错。

2.比较整个时间，不取出当前日期进行比较，有bug：

var lifeWorkEventBatch = clientRepositoryContainer.LifeWorkEventBatchRepository.FindAll(lfe => lfe.SelectionStartTime <= DateTime.Now && lfe.SelectionEndTime >= DateTime.Now).FirstOrDefault();

该linq转化为sql语句为：

    SELECT
    [Extent1].[pkLifeWorkEventBatch] AS [pkLifeWorkEventBatch],
    [Extent1].[LifeWorkEventBatchCode] AS [LifeWorkEventBatchCode],
    [Extent1].[SelectionStartTime] AS [SelectionStartTime],
    [Extent1].[SelectionEndTime] AS [SelectionEndTime],
    [Extent1].[Status] AS [Status],
    [Extent1].[Description] AS [Description],
    [Extent1].[CreateOn] AS [CreateOn],
    [Extent1].[CreateBy] AS [CreateBy],
    [Extent1].[LastModifyOn] AS [LastModifyOn],
    [Extent1].[LastModifyBy] AS [LastModifyBy]
    FROM [dbo].[LifeWorkEventBatch] AS [Extent1]
    WHERE ([Extent1].[SelectionStartTime] <= (SysDateTime())) AND ([Extent1].[SelectionEndTime] >= (SysDateTime()))

3.实现需求的无错版本：

var dateTimeNow = DateTime.Now;
                var lifeWorkEventBatch = clientRepositoryContainer.LifeWorkEventBatchRepository.FindAll(lfe => lfe.SelectionStartTime <= dateTimeNow && lfe.SelectionEndTime >= dateTimeNow.Date).FirstOrDefault();

转化后的sql

exec sp_executesql N'SELECT
    [Extent1].[pkLifeWorkEventBatch] AS [pkLifeWorkEventBatch],
    [Extent1].[LifeWorkEventBatchCode] AS [LifeWorkEventBatchCode],
    [Extent1].[SelectionStartTime] AS [SelectionStartTime],
    [Extent1].[SelectionEndTime] AS [SelectionEndTime],
    [Extent1].[Status] AS [Status],
    [Extent1].[Description] AS [Description],
    [Extent1].[CreateOn] AS [CreateOn],
    [Extent1].[CreateBy] AS [CreateBy],
    [Extent1].[LastModifyOn] AS [LastModifyOn],
    [Extent1].[LastModifyBy] AS [LastModifyBy]
    FROM [dbo].[LifeWorkEventBatch] AS [Extent1]
    WHERE ([Extent1].[SelectionStartTime] <= @p__linq__0) AND ([Extent1].[SelectionEndTime] >= @p__linq__1)',N'@p__linq__0 datetime2(7),@p__linq__1 datetime2(7)',@p__linq__0='2019-07-31 12:52:40.5630849',@p__linq__1='2019-07-31 00:00:00'

从两次转化后的sql语句可以看出，先获取系统日期，再在linq中使用，则直接转化成为了日期类型的参数。