LINQ to SQL连接顺序

Question

i am new to LINQ and joins, so Please forgive me if I am asking it wrong. I have two tables

Table1

id   name    date
1    Mike    20-10-15
2    John    21-10-15
3    Sam     23-10-15

Table2

id   name   date
1    Ashle  19-10-15
2    Lily   21-10-15
3    Jeni   22-10-15
4    April  23-10-15

I need 5 records using Joins and should be orderby Date, most recent records.

Can you guys help me, I really need to figure out how Joins works with orderby. Thanks

EDIT: They are two different tables so no foreign key, so I think I can't use Join, so so far what I have done is like this

var combinddata = (from t1 in db.Table1
                        select t1.id)
                            .Concat(from t2 in db.Table2
                                    select t2.id);

I don't know how to get only 5 records how to compare records from both tables on DateTime base.

Output should be

1. Sam
2. April
3. Jeni
4. John
5. Lily

Answer 1

You can concatenate equal anonymous types from different tables. If you also select the dates, you can sort by them, in descending order, and take the first 5 records:

Table1.Select (t1 => 
    new
    {
        Id = t1.Id,
        Name = t1.Name,
        Date = t1.Date
    }
).Concat(
Table2.Select (t2 => 
    new
    {
        Id = t2.Id,
        Name = t2.Name,
        Date = t2.Date
    }
))
.OrderByDescending (x => x.Date).Take(5)

Note that this gives precedence to items in Table1 . If item 5 and 6 in the concatenated result are on the same date, but from Table1 and Table2 , respectively, you only get the item from Table1 .

If you want, you can select only the names from this result, but I assume that your output only shows the intended order of record, not the exact expected result.

Answer 2

Try this way

var combinddata = (from t1 in db.Table1
                        select t1.Name)
                            .Concat(from t2 in  db.Table2 
                                    select t2.Name).OrderByDescending(x => x.date).Take(5);

Answer 3

var query = 
    from Table1 in table1
    join Table2 in table2 on table1.id equals table2.id 
    orderby table1.date ascending 
    select table1.date;