具有完全外部联接的 SQL 到 LINQ 转换

本文关键字：SQL LINQ 转换 外部 | 更新日期: 2023-09-27 18:31:59

SELECT* FROM Event FULL OUTER JOIN Booking ON Event.eventId = Booking.eventId
WHERE(Booking.userId = 3) AND (Booking.bookingId IS NULL) 
OR (Event.eventId IS NULL) 
OR (Booking.eventId IS NULL)

这是我到目前为止转换的内容，但是我在"&& bookings.bookingId == null"处遇到错误

，错误消息是" 运算符 '&&' 不能应用于类型为 'int' 和 'bool' 的操作数

你如何解决它？

            User student = (User)Session["user"];
        var db = new EMS.Models.dbEMSEntities();
        IQueryable<Event> query =  from events in db.Events
                                   join bookings in db.Bookings
                                   on events.eventId equals bookings.eventId
                                   where bookings.userId = student.userId 
                                   && bookings.bookingId == null || events.eventId == null || bookings.eventId == null

具有完全外部联接的 SQL 到 LINQ 转换

where bookings.userId = student.userId && bookings.bookingId == null || events.eventId == null || bookings.eventId == null

正在评估为 

where bookings.userId = (student.userId && bookings.bookingId == null) || events.eventId == null || bookings.eventId == null

因此，（int）userId && （bool）（bookingId == null） 将int与违反语言的bool进行比较确保使用"=="作为评估，而不是分配"="。

   User student = (User)Session["user"];
        var db = new EMS.Models.dbEMSEntities();
        IQueryable<Event> query =  from events in db.Events
                                   join bookings in db.Bookings
                                   on events.eventId equals bookings.eventId
                                   where (bookings.userId == student.userId)
                                   && (bookings.bookingId == null) || (events.eventId == null) || (bookings.eventId == null)
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