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在景点的住宿集合（Lodgings）中增加一个度假区（Resort）
1 2 3 4 5 6 7 8 9 | var dest = (from d in context.Destinations where d.Name == "Bali" select d).Single();var resort = new CodeFirst.Model.Resort{ Name = "Pete's Luxury Resort",};dest.Lodgings.Add(resort);context.SaveChanges(); |
添加一个带两个住宿的景点
1 2 3 4 5 6 7 8 9 10 11 | var destination = new CodeFirst.Model.Destination{ Name = "AnHui HuangShan", Lodgings = new List { new CodeFirst.Model.Lodging {Name="HuangShan Hotel"}, new CodeFirst.Model.Lodging {Name="YingKeSong Hotel"} }};context.Destinations.Add(destination);context.SaveChanges(); |
添加一个带有景点信息度假村到住宿信息中。
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 | var resort = new CodeFirst.Model.Resort{ Name = "Top Notch Resort and Spa", Destination = new CodeFirst.Model.Destination { Name = "Stowe, Vermont", Country = "USA" }};using (var context = new CodeFirst.DataAccess.BreakAwayContext()){ context.Lodgings.Add(resort); context.SaveChanges();} |
1 2 3 4 5 | var hotel = (from l in context.Lodgings where l.Name == "YingKeSong Hotel" select l).Single();var reef = (from d in context.Destinations where d.Name == "Bali" select d).Single();hotel.Destination = reef;context.SaveChanges(); |
1、ForeignKeys方式：
1 2 3 | var davesDump = (from l in context.Lodgings where l.Name == "HuangShan Hotel" select l).Single();davesDump.DestinationID = null;//(ForeignKeys方式）context.SaveChanges(); |
2、Reference方式：
1 2 3 4 | var davesDump = (from l in context.Lodgings where l.Name == "HuangShan Hotel" select l).Single();context.Entry(davesDump).Reference(l => l.Destination).Load(); //找主表数据davesDump.Destination = null; //清空,(Reference方式）context.SaveChanges(); |
如果数据库里设置是级联删除，则不显示加载从表数据。
1 2 3 4 5 | var canyon = (from d in context.Destinations where d.Name == "AnHui HuangShan" select d).Single();context.Entry(canyon).Collection(d => d.Lodgings).Load(); //从表显示加载后，再删除主表数据context.Destinations.Remove(canyon);context.SaveChanges(); |
删除主表数据，同时标注从表数据为删除状态（数据库关闭了级联删除的情况，可以手动去数据库的外键关系修改，也可以Fluent API配置关闭级联删除）
1 2 3 4 5 6 7 8 | var canyon = (from d in context.Destinations where d.Name == "Grand Canyon" select d).Single();foreach (var lodging in canyon.Lodgings.ToList()){ context.Lodgings.Remove(lodging); //先标记相关的从表数据为删除状态}context.Destinations.Remove(canyon); //再标记主表数据为删除装填context.SaveChanges(); //执行上面的所有标记 |
到此这篇关于Entity Framework主从表增删改的文章就介绍到这了。希望对大家的学习有所帮助，也希望大家多多支持脚本之家。
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