How do I get the max ID with Linq to Entity

Question

I have a table User which has an identity column UserID  now what is the correct Linq to Entity line of code that would return me the max UserID   I ve tried   using  MyDBEntities db   new MyDBEntities          var User   db Users Last           or     var User   db Users Max         return user UserID      but Last and Max don t seem to be supported   Any ideas

User · Answer

try this  int intIdt   db Users Max u   gt  u UserId     Update   If no record then generate exception using above code try this  int  intIdt   db Users Max u   gt   int  u UserId

User · Answer

Do that like this  db Users OrderByDescending u   gt  u UserId  FirstOrDefault

User · Answer

var max   db Users DefaultIfEmpty   Max r   gt  r    null   0   r ModelID     when there are no records in db it would return 0 with no exception

User · Answer

Do that like this  db Users OrderByDescending u   gt  u UserId  FirstOrDefault

User · Answer

In case if you are using the async and await feature  it would be as follows   User currentUser   await db Users OrderByDescending u   gt  u UserId  FirstOrDefaultAsync

User · Answer

The best way to get the id of the entity you added is like this   public int InsertEntity Entity factor        Db Entities Add factor       Db SaveChanges        var id   factor id      return id

User · Answer

Do that like this  db Users OrderByDescending u   gt  u UserId  FirstOrDefault

User · Answer

Note that none of these answers will work if the key is a varchar since it is tempting to use MAX in a varchar column that is filled with  quot ints quot   In a database if a column e g   quot Id quot  is in the database 1 2 3  110  112  113  4  5  6 Then all of the answers above will return 6  So in your local database everything will work fine since while developing you will never get above 100 test records  then  at some moment during production you get a weird support ticket  Then after an hour you discover exactly this line  quot max quot  which seems to return the wrong key for some reason      and note that it says nowhere above that the key is INT      and if happens to end up in a generic library     So use  Users OrderByDescending x  gt x Id Length  ThenByDescending a   gt  a Id  FirstOrDefault

User · Answer

Note that none of these answers will work if the key is a varchar since it is tempting to use MAX in a varchar column that is filled with  quot ints quot   In a database if a column e g   quot Id quot  is in the database 1 2 3  110  112  113  4  5  6 Then all of the answers above will return 6  So in your local database everything will work fine since while developing you will never get above 100 test records  then  at some moment during production you get a weird support ticket  Then after an hour you discover exactly this line  quot max quot  which seems to return the wrong key for some reason      and note that it says nowhere above that the key is INT      and if happens to end up in a generic library     So use  Users OrderByDescending x  gt x Id Length  ThenByDescending a   gt  a Id  FirstOrDefault

User · Answer

Do that like this  db Users OrderByDescending u   gt  u UserId  FirstOrDefault

User · Answer

try this  int intIdt   db Users Max u   gt  u UserId     Update   If no record then generate exception using above code try this  int  intIdt   db Users Max u   gt   int  u UserId

User · Answer

NisaPrieto   Users user   bd Users Where u  gt  u UserAge  gt  21  Max u   gt  u UserID      will not work because MAX returns the same type of variable that the field is so in this case is an INT not an User object

User · Answer

var max   db Users DefaultIfEmpty   Max r   gt  r    null   0   r ModelID     when there are no records in db it would return 0 with no exception

User · Answer

In case if you are using the async and await feature  it would be as follows   User currentUser   await db Users OrderByDescending u   gt  u UserId  FirstOrDefaultAsync

User · Answer

NisaPrieto   Users user   bd Users Where u  gt  u UserAge  gt  21  Max u   gt  u UserID      will not work because MAX returns the same type of variable that the field is so in this case is an INT not an User object

User · Answer

The best way to get the id of the entity you added is like this   public int InsertEntity Entity factor        Db Entities Add factor       Db SaveChanges        var id   factor id      return id

[c#] How do I get the max ID with Linq to Entity?

Examples related to c#

Examples related to linq

Examples related to entity-framework

Examples related to linq-to-entities