C＃实体框架字符串规范函数

Question

How to use the Right function in entity framework query? I have this sql query

SELECT RIGHT('0' + '4'), DATEDIFF(MINUTE, DateReceived, GETDATE()) % 60), 2)  
FROM mytable //RESULTS = 04

The Right function will basically add 0 infront if the passed string's length is less than 2.

Now I want to do the same thing in entity framework query:

var query = (from b in sovDB.myTable
select new
{
    myMinutes = Right("0"+ (SqlFunctions.DateDiff("MINUTE", b.DateReceived,  
    SqlFunctions.GetDate()) % 60),2)
}).ToList();

But it doesnt work, somehow the Right function is not supported.

Answer 1

Just had the same issue when converting an old stored procedure to entity. I used SqlFunctions.Replicate which did the trick and Entity Framework had no complaints!

var query = (from b in sovDB.myTable
select new
{
    myMinutes = SqlFunctions.Replicate("0", 2 - (SqlFunctions.DateDiff("MINUTE", b.DateReceived, GetDate()) % 60).Length) + (SqlFunctions.DateDiff("MINUTE", b.DateReceived, GetDate()) % 60)
}).ToList();

Answer 2

Try to explicitly convert calculated minute to string:

var query = (from b in sovDB.myTable
select new
{
    myMinutes = Right("0" + SqlFunctions.StringConvert((int)(SqlFunctions.DateDiff("MINUTE", b.DateReceived, SqlFunctions.GetDate()) % 60)), 2)
}).ToList();