Question

您好我有三个已加入的表，但即使假设有一些结果，它也会返回空结果。这是我的sql

SELECT c.code,c.name, a.ltp as begning, b.ltp as enddate, d.interim_cash,d.interim_rec_date,
CAST(((b.ltp - a.ltp) / a.ltp * 100) AS DECIMAL(10, 2)) as chng
FROM eod_stock a
JOIN eod_stock b ON a.company_id = b.company_id
LEFT OUTER JOIN company AS c
ON c.ID = a.company_id
RIGHT JOIN divident_info AS d
ON c.ID = d.company_id
WHERE a.entry_date = "2012-09-24"
AND b.entry_date = "2012-09-25"
AND d.interim_rec_date BETWEEN "2012-09-24" AND "2012-09-25"
AND a.company_id IN (13, 2)
AND d.company_id IN (13,2);

我期待的结果是这样的：

+--------+-----------------+---------+--------+--------+------------------+------------+
| code   | name            | begning | end    | chng   | interim_rec_date |interim_cash|
+--------+-----------------+---------+--------+--------+------------------+------------+
| ABBANK | AB BANK LIMITED |  518.00 | 459.00 | -11.39 |2012-09-24        |10          |
| 1STICB | 1ST ICB M.F.    |  227.00 | 253.00 |  11.45 |                  |            |
+--------+-----------------+---------+--------+--------+------------------+------------+

但是我的结果是空的，因为第二个临时信息是0？如果行为空，我怎么能得到上面的所有信息然后它可能是空白但我需要与之相关的其他信息。

以下是我的表架构：

eod_stock：

+-----------------+------------------+------+-----+---------+-------+
| Field           | Type             | Null | Key | Default | Extra |
+-----------------+------------------+------+-----+---------+-------+
| company_id      | varchar(30)      | NO   | PRI | NULL    |       |
| entry_date      | date             | NO   | PRI | NULL    |       |
| entry_timestamp | int(10) unsigned | NO   |     | NULL    |       |
| open            | decimal(16,2)    | NO   |     | NULL    |       |
| high            | decimal(16,2)    | NO   |     | NULL    |       |
| low             | decimal(16,2)    | NO   |     | NULL    |       |
| ltp             | decimal(16,2)    | NO   |     | NULL    |       |
| ycp             | decimal(16,2)    | NO   |     | NULL    |       |
| cse_price       | decimal(9,2)     | NO   |     | NULL    |       |
| cse_volume      | decimal(18,2)    | NO   |     | NULL    |       |
| total_trade     | int(30)          | NO   |     | NULL    |       |
| total_volume    | int(30)          | NO   |     | NULL    |       |
| total_value     | decimal(18,4)    | NO   |     | NULL    |       |
+-----------------+------------------+------+-----+---------+-------+

divident信息：

+------------------+--------------+------+-----+-------------------+-----------------------------+
| Field            | Type         | Null | Key | Default           | Extra                       |
+------------------+--------------+------+-----+-------------------+-----------------------------+
| divident_ID      | int(11)      | NO   | PRI | NULL              | auto_increment              |
| company_id       | int(11)      | NO   |     | NULL              |                             |
| year             | year(4)      | NO   |     | NULL              |                             |
| right_base       | int(11)      | NO   |     | NULL              |                             |
| right_new        | int(11)      | NO   |     | NULL              |                             |
| right_dec_date   | date         | NO   |     | NULL              |                             |
| right_rec_date   | date         | NO   |     | NULL              |                             |
| interim_cash     | decimal(6,2) | NO   |     | NULL              |                             |
| interim_stock    | decimal(8,2) | NO   |     | NULL              |                             |
| interim_dec_date | date         | NO   |     | NULL              |                             |
| interim_rec_date | date         | NO   |     | NULL              |                             |
| annual_cash      | decimal(6,2) | NO   |     | NULL              |                             |
| annual_stock     | decimal(8,2) | NO   |     | NULL              |                             |
| annual_dec_date  | date         | NO   |     | NULL              |                             |
| annual_rec_date  | date         | NO   |     | NULL              |                             |
| update_time      | timestamp    | NO   |     | CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP |
+------------------+--------------+------+-----+-------------------+-----------------------------+

请你能帮我找出结果吗？

Answer 1

这是您的查询：

SELECT c.code,c.name, a.ltp as begning, b.ltp as enddate, d.interim_cash,d.interim_rec_date,
       CAST(((b.ltp - a.ltp) / a.ltp * 100) AS DECIMAL(10, 2)) as chng
FROM eod_stock a JOIN
     eod_stock b
     ON a.company_id = b.company_id LEFT OUTER JOIN
     company AS c
     ON c.ID = a.company_id RIGHT JOIN
     divident_info d
     ON c.ID = d.company_id
WHERE a.entry_date = "2012-09-24" AND
      b.entry_date = "2012-09-25" AND
      d.interim_rec_date BETWEEN "2012-09-24" AND "2012-09-25" AND
      a.company_id IN (13, 2) AND
      d.company_id IN (13, 2);

就我个人而言，我发现很难跟踪left join与right join混合的查询：只使用left join更容易建立结构，这样您就可以轻松看到table驱动查询。

在任何情况下，您的where子句都会撤消外连接的影响。除了您明确列出的条件之外，您还要说：

a.entry_date is not null and
b.entry_date is not null and
d.interim_rec_date is not null and
a.company_id is not null and
d.company_id is not null

很难说您需要消除哪些条件才能获得所需的结果。我可以说的是，其中一些应该进入on条款而不是where条款。这是最好的解决方案。您也可以将where更改为：

WHERE a.entry_date = "2012-09-24" AND
      b.entry_date = "2012-09-25" AND
      d.interim_rec_date BETWEEN "2012-09-24" AND "2012-09-25" AND
      a.company_id IN (13, 2) AND
      d.company_id IN (13, 2) AND
      (a.entry_date is null  or a.company_id is null or b.entry_date is null)

但是，您可能只需要其中一个或两个条件。请注意d条件中的条件应保留在where子句中，因为right outer join将所有行保留在d中，因此不会NULL（除非{原始数据中的{1}}。

Answer 2

试试这个：

SELECT c.code,c.name, a.ltp as begning, b.ltp as enddate, 
d.interim_cash,d.interim_rec_date,
CAST(((b.ltp - a.ltp) / a.ltp * 100) AS DECIMAL(10, 2)) as chng
FROM eod_stock a
JOIN eod_stock b ON a.company_id = b.company_id
LEFT OUTER JOIN company AS c
ON c.ID = a.company_id
RIGHT JOIN divident_info AS d
ON c.ID = d.company_id AND d.interim_rec_date BETWEEN "2012-09-24" AND "2012-09-25"
AND d.company_id IN (13,2)    
WHERE a.entry_date = "2012-09-24"
AND b.entry_date = "2012-09-25"
AND a.company_id IN (13, 2);

Answer 3

所以最后我得到了我需要的是查询：

 SELECT c.code,c.name, a.ltp as begning, b.ltp as enddate, d.interim_cash,d.interim_rec_date,      d.annual_rec_date,d.annual_cash,
 CAST(((b.ltp - a.ltp) / a.ltp * 100) AS DECIMAL(10, 2)) as chng
 FROM eod_stock AS a

 LEFT OUTER JOIN eod_stock AS b
 ON a.company_id = b.company_id

 LEFT OUTER JOIN company AS c
 ON c.ID = a.company_id

 LEFT OUTER JOIN dividend_info AS d
 ON c.ID = d.company_id AND d.interim_rec_date BETWEEN "2012-09-24" AND "2012-09-25" AND       d.annual_rec_date BETWEEN "2012-09-24" AND "2012-09-25"

 WHERE a.entry_date = "2013-09-24"
 AND b.entry_date = "2013-09-25"
 AND a.company_id IN (13, 2,4,5);

感谢Gordon Linoff带我走上正轨，我正在弄乱正确的加入

Mysql三表连接结果为空集

3 个答案: