SQL：多行總和以更新初始表

Question

下面不斷給我錯誤，我已經解決了這個問題，但是我沒有指出什么是錯誤的/如何解決的。

t1

    c1 c2

    1 -

    2 -

t2

    c1 c2

    1 - 3

    1 - 2

    2 - 2

    2 - 2

    UPDATE T1 a, t2 b SET a.c2 = sum(b.c2)
    GROUP BY b.c1 HAVING b.c1 = a.c1;

Answer 1

您可以嘗試以下方法：

UPDATE T1
SET c2 = (SELECT SUM(c2) FROM T2 WHERE c1 = T1.c1)

Answer 2

這個怎么樣：

UPDATE a SET a.c2 = sum(b.c2)
FROM T1 a INNER JOIN t2 b ON a.c1 = b.c1     
GROUP BY b.c1

Answer 3

試試這個：

      UPDATE T1
      set a.c2= b.c2 from T1 a inner JOIN 
     (select c1, sum(c2) from T2 group by c1) b on a.c1 = b.c1;