Question

我有以下表结构：

+------+-------+-------+--------+
| mid  | a     | b     | points |
+------+-------+-------+--------+
|   69 |  3137 | 13316 |    210 |
|   70 | 13316 |  3137 |    350 |
|   71 |  3497 | 13316 |    200 |
|   72 | 13316 |  3497 |     25 |
|   73 |  3605 | 13316 |    205 |
|   74 | 13316 |  3605 |    290 |
+------+-------+-------+--------+

我想在行1的“a”=第2行的“b”和第2行的“a”=第1行的“b”时添加两行的“points”值。

输出必须是这样的：

+------+-------+-------+--------+
| mid  | a     | b     | points |
+------+-------+-------+--------+
|   69 |  3137 | 13316 |    560 |
|   71 |  3497 | 13316 |    225 |
|   73 |  3605 | 13316 |    495 |
+------+-------+-------+--------+

Answer 1

如果我理解正确，那么你想要：

SELECT p1.mid, p1.a, p1.b, p1.points + p2.points points
FROM points p1 
INNER JOIN points  p2 ON p1.a = p2.b  AND p1.b = p2.a
WHERE p1.mid < p2.mid

我已在sql fiddle中将其删除并提供您想要的输出。

Answer 2

你可以这样试试

SELECT t1.mid, t1.a, t1.b, t1.points + t2.points points
  FROM table1 t1 JOIN table1 t2
    ON t1.a = t2.b
   AND t1.b = t2.a
   AND t1.mid < t2.mid

或利用MySQL非标准GROUP BY扩展名

SELECT mid, a, b, SUM(points) points
  FROM
(
  SELECT mid, a, b, points
    FROM table1
   ORDER BY mid
) q
 GROUP BY LEAST(a, b), GREATEST(a, b)

输出：

| MID |    A |     B | POINTS |
|-----|------|-------|--------|
|  69 | 3137 | 13316 |    560 |
|  71 | 3497 | 13316 |    225 |
|  73 | 3605 | 13316 |    495 |

这是 SQLFiddle 演示

根据mysql中的条件添加两行的列

2 个答案: