Compare two sql dates using Linq

Question

I need to compare two dates that are on SQLServer, to see if the user has already logged after 10 seconds of his register on the system, but when I try this query, it gives me a

NotSupportedException [System.NotSupportedException] = {"System.DateTime AddSeconds(Double)"}

Query:

var query = from user in this.Query()
            where (user.LastLoginDate.AddSeconds(-10) <= user.CreateDate) 
            select std;

possible duplicate of [How to use DATEADD over column in LINQ - DateAdd is not recognized by LINQ](http://stackoverflow.com/questions/17371798/how-to-use-dateadd-over-column-in-linq-dateadd-is-not-recognized-by-linq) — Caramiriel, Jan 16 '15 at 15:10
the problem is that I'm comparing two SQLDates. It is linq-to-sql — Saliba, Jan 16 '15 at 15:12
This is a non-issue. In LINQ-to-SQL it's supported. It's not clear if OP have their tags right and below the accepted answer there is a vague comment "I managed to change the requirements". Voting to close as not reproducible. — Gert Arnold, Jul 05 '21 at 11:04

score 0 · Accepted Answer · answered Jan 16 '15 at 15:48

Well here is really dirty (and probably bad perfomance if you don't have indexes) way to solve your problem but it should work:

var query = from user in this.Query()
            where ((user.LastLoginDate.Date == user.CreateDate.Date
                && user.LastLoginDate.Hour == user.CreateDate.Hour
                && user.LastLoginDate.Minute == user.CreateDate.Minute
                && user.LastLoginDate.Second <= user.CreateDate.Second + 10)
                ||(user.LastLoginDate.Date == user.CreateDate.Date
                && user.LastLoginDate.Hour == user.CreateDate.Hour
                && user.LastLoginDate.Minute + 1 == user.CreateDate.Minute
                && 60 - user.CreateDate.Second + user.LastLoginDate.Second <= 10)) 
            select std;

I think you get the idea.

Yea, that woud work, but it's complex, but I managed to change the requirements, thanks — Saliba, Jan 19 '15 at 14:43

Compare two sql dates using Linq

1 Answers1