使用LINQ通過兩個關鍵列聯接兩個數據表

Question

數據表A：

Key1 | Key2 | A | 乙

[1 1 ...]

[1 2 ...]

數據表B：

Key1 | Key2 | x | ÿ

[1 1 ...]

[1 2 ...]

所需結果：

Key1 | Key2 | A | B | X | ÿ

[1 1 ...]

[1 2 ...]

在最終結果中，列A，B，X和Y已添加到新數據表中。 發生這種情況是因為在數據表A和B中key1和key2相等。給定條件-（Key1和Key2是等價的），是否可以使用完全外部聯接？

Answer 1

試試這個代碼的朋友：

var req = (from A in DatatableA
       join B in DatatableB 
        on A.Key1
            equals B.Key1  into DatatableResult
            select new
           {
                  Key1 = A.Key1    ,
                 Key2 = A.Key2    ,
               A= A.A ,
               x= B.x ,
               y= B.y ,

             }).ToList();

Answer 2

var list1 = (from t1 in dataTable1.AsEnumerable()
                select new
                {
                    Key1 = t1.Field<int>("Key1"),
                    Key2 = t1.Field<int>("Key2"),
                    A = t1.Field<string>("A"),
                    B = t1.Field<string>("B")
                });

var list2 = (from b in dataTable2.AsEnumerable()
                select new
                {
                    Key1 = b.Field<int>("Key1"),
                    Key2 = b.Field<int>("Key2"),
                    X = b.Field<string>("X"),
                    Y = b.Field<string>("Y")
                });

// Now join the 2 collections and get the result you want.

var result = (from x in list1
                join y in list2 on new { x.Key1,x.Key2} equals new { y.Key1,y.Key2 }
                select new { A = x.A, X = y.X }).ToList();

假設Key1和Key2為int類型，而AB，X和Y為string類型。