Question

I have been doing queries in EF and everything working great but now i have in the db 2 fields that are actually CHAR.. They hold a date but in the form of a number, in SQL Management Studio i can do date1 >= date2 for example and i can also check to see if a number i have falls in between these 2 dates.

Its nothing unusual, but basically a field that represents a date (the number grows as the date does)…

Now in EF when i try to do >= it states you can’t do this on a string, ok understand its c# so i tried doing Convert.ToDecimal(date1) but it gives me an error saying that its not supported.

I have no option of changing the db fields, they are set in stone 🙁

the way i got it to work was request of details and do a .ToList and then use the .ToDecimal and it works but of course this is doing it in memory! and this defeats the object of EF i.e. for example adding to the query using iqueryable.

Another way i got it to work was to pass the SQL query to SqlQuery of the dbcontext but again i lose a lot of ef functionality.

Can anyone help?

I am really stuck

Answer 1

As you say that you tried >= I assume that it would work for you if you could do that in plain SQL. And that is possible by doing

String.Compare(date1, date2) >= 0

EF is smart enough to translate that into a >= operator.

The advantage is that you do not need to compare converted values, so indexes can be used in execution plans.