將標題重寫為：使用反向值對列進行SQL分組

Question

假設我有一個像這樣的表：

+---+---+---+---+---+
|G1 |G2 |G3 |G4 | V |
+---+---+---+---+---+
| A | B | C | D | 2 |
| E | F | G | H | 4 |
| C | D | A | B | 2 |
| E | F | G | H | 3 |
| E | I | G | L | 7 |
+---+---+---+---+---+

其中G1、G3是VARCHAR型，G2、G4是INT型別

如果我在G1..G4上進行簡單的GROUP BY，我會得到：

SELECT G1,G2,G3,G4,SUM(V) as V FROM Table GROUP BY G1, G2, G3, G4;

    +---+---+---+---+---+
    |G1 |G2 |G3 |G4 | V |
    +---+---+---+---+---+
    | A | B | C | D | 2 |
    | E | F | G | H | 7 |
    | C | D | A | B | 2 |
    | E | I | G | L | 7 |
    +---+---+---+---+---+

我想知道是否可能在反轉的值G1、G2 <-> G3、G4上進行聚合。 我想要的結果是這樣的：

+---+---+---+---+---+      +---+---+---+---+---+
|G1 |G2 |G3 |G4 | V |      |G1 |G2 |G3 |G4 | V |
+---+---+---+---+---+      +---+---+---+---+---+
| A | B | C | D | 4 |  或  | C | D | A | B | 4 |
| E | F | G | H | 7 |      | E | F | G | H | 7 |
| E | I | G | L | 7 |      | E | I | G | L | 7 |
+---+---+---+---+---+      +---+---+---+---+---+

我嘗試取得反轉的行，但由於重複，我仍然無法在它們上進行聚合。我的測試查詢是：

SELECT DISTINCT *
FROM Table t1
JOIN Table t2 on t1.G1 = t2.G3 and t1.G2=t2.G4 and t1.G3=t2.G1 and t1.G4=t2.G2

    +---+---+---+---+---+---+---+---+---+---+
    |G1 |G2 |G3 |G4 | V |G1 |G2 |G3 |G4 | V |
    +---+---+---+---+---+---+---+---+---+---+
    | A | B | C | D | 2 | C | D | A | B | 2 |
    | C | D | A | B | 2 | A | B | C | D | 2 |
    +---+---+---+---+---+---+---+---+---+---+

Answer 1

如果我理解正確，將列的順序反轉，使得 A B C D 對應 C D A B。

select 
         case when(g1 > g3) then g3 else g1 end G1,
         case when(g1 > g3) then g4 else g2 end G2,
         case when(g1 > g3) then g1 else g3 end G3,
         case when(g1 > g3) then g2 else g4 end G4, sum(V)
from tbl
group by case when(g1 > g3) then g3 else g1 end,
         case when(g1 > g3) then g4 else g2 end,
         case when(g1 > g3) then g1 else g3 end,
         case when(g1 > g3) then g2 else g4 end

db<>fiddle

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