如何使EF存在查询？

Question

我有两个列表rtrn和Zipcodes

rtnr项目有Utility字段。我需要返回rtrn的子集rtrn.Utility field1或filed2或field3 zipocode项

Answer 1

1. 从此zipcodes文件中获取独特的实用程序1-3

       DbSet<Utility> utilities;
       DbSet<Zipcodes> zipcodes;
   
       var uniqeUtilitiesInZipcodes = zipcodes.Select(x => x.Field1).ToList();
       uniqeUtilitiesInZipcodes.AddRange(zipcodes.Select(x => x.Field2).ToList());
       uniqeUtilitiesInZipcodes.AddRange(zipcodes.Select(x => x.Field3).ToList());
   
       uniqeUtilitiesInZipcodes = uniqeUtilitiesInZipcodes.Distinct().ToList();
   

2. 将独特的实用程序与zipcodes相交

       uniqeUtilitiesInZipcodes = uniqeUtilitiesInZipcodes.Distinct().ToList();
   
       var zipcodesWhereUtilityExistsInAnyUtiltyField = utilities.Intersect(uniqeUtilitiesInZipcodes).ToList();