Question

这个问题继续我之前的问题。

这一次，情况是这样的

TableA
+-------------------+--------+
| wordA(primarykey) | countA |
+-------------------+--------+
| pqr               |      5 |
| abcd              |     20 |
| pqrs              |     45 |
+-------------------+--------+

TableB
+-------------------+--------+
| wordB(primarykey) | countB |
+-------------------+--------+
| pq                |     10 |
| abc               |     10 |
| pqrs              |     10 |
| abcdef            |      5 |
+-------------------+--------+

这次TableC已经有了这些元组。如果TableC中已存在任何单词，则其计数将增加TableA或TableB的值。如果没有，则将新单词添加到其中。这就像我们正在更新表并插入更新未完成。

TableC(before query)
+--------+--------+--------+
|  word  | countA | countB |
+--------+--------+--------+
| ab     |      0 |     10 |
| abc    |     25 |     40 |
| abcd   |     29 |      0 |
| abcde  |     45 |     90 |
| abcdef |      0 |     55 |
+--------+--------+--------+

Desired output:
TableC(after query)
+--------+--------+--------+
|  word  | countA | countB |
+--------+--------+--------+
| ab     |      0 |     10 |
| abc    |     25 |     50 |
| abcd   |     49 |      0 |
| abcde  |     45 |     90 |
| abcdef |      0 |     60 |
| pq     |      0 |     10 |
| pqr    |      5 |      0 |
| pqrs   |     45 |     10 |
+--------+--------+--------+

Answer 1

在MySQL中，如果使用ON DUPLICATE KEY语法TableC.Word是PRIMARY KEY，则可以在一个查询中执行此操作：

SQLFiddle demo

INSERT INTO TableC(Word,CountA,CountB)

SELECT * FROM
(
SELECT Word,SUM(CountA) as Ca,SUM(CountB) as Cb 
FROM
(
  SELECT WordA as Word,CountA, 0 as CountB FROM TableA
   UNION ALL
  SELECT WordB as Word,0 as CountA, CountB FROM TableB
) T GROUP BY Word  
) T1  

ON DUPLICATE KEY 
UPDATE CountA = CountA+T1.Ca,CountB = CountB+T1.Cb

Answer 2

使用 ON DUPLICATE KEY UPDATE 试试这可能对您有所帮助。

INSERT INTO 'your previos query'
ON DUPLICATE KEY UPDATE 
  countA = coutnA +1

更新表，如果不存在然后插入

2 个答案: