Mysql 连接两个表,合并并转置结果
好的,假设我有两个表Mysql 连接两个表,合并并转置结果,mysql,inner-join,transpose,Mysql,Inner Join,Transpose,好的,假设我有两个表products和product\u选项 结构表产品如下: +--------------------------------------+ | p_id | product_name | product_status | +--------------------------------------+ | 1 | Keyboard ABC | PENDING | | 2 | Mouse ABC | ORDERED
products
和product\u选项
结构表产品如下:
+--------------------------------------+
| p_id | product_name | product_status |
+--------------------------------------+
| 1 | Keyboard ABC | PENDING |
| 2 | Mouse ABC | ORDERED |
| 3 | Monitor ABC | ORDERED |
+--------------------------------------+
+--------------------------------------+
| po_id | p_id | opt_name | opt_value +
+--------------------------------------+
| 1 | 1 | part_no | KB-ABC-001 |
| 2 | 1 | stock | 0 |
| 3 | 2 | part_no | MS-ABC-001 |
| 4 | 2 | stock | 14 |
| 5 | 3 | part_no | MO-ABC-001 |
| 6 | 3 | stock | 10 |
+--------------------------------------+
和表产品选项
类似:
+--------------------------------------+
| p_id | product_name | product_status |
+--------------------------------------+
| 1 | Keyboard ABC | PENDING |
| 2 | Mouse ABC | ORDERED |
| 3 | Monitor ABC | ORDERED |
+--------------------------------------+
+--------------------------------------+
| po_id | p_id | opt_name | opt_value +
+--------------------------------------+
| 1 | 1 | part_no | KB-ABC-001 |
| 2 | 1 | stock | 0 |
| 3 | 2 | part_no | MS-ABC-001 |
| 4 | 2 | stock | 14 |
| 5 | 3 | part_no | MO-ABC-001 |
| 6 | 3 | stock | 10 |
+--------------------------------------+
问题是,我想显示这两个查询表,并且只显示我订购的产品的特定条件。结果可能是:
+------------------------------------------------------------+
| p_id | product_name | part_no | stock | product_status |
+------------------------------------------------------------+
| 2 | Mouse ABC | MS-ABC-001 | 14 | ORDERED |
| 3 | Monitor ABC | MO-ABC-001 | 10 | ORDERED |
+------------------------------------------------------------+
我的SQL查询是:
SELECT
t.p_id,
t.product_name,
(CASE WHEN t.key_name = 'part_no' THEN t.key_value ELSE NULL END) AS part_no,
(CASE WHEN t.key_name = 'stock' THEN t.key_value ELSE NULL END) AS stock,
t.product_status
FROM
(
SELECT
products.p_id as p_id,
products.product_name as product_name,
products.product_status as product_status,
product_options.opt_name as key_name,
product_options.opt_value as key_value
FROM
product_options Inner Join
products On product_options.p_id = products.p_id
WHERE
(products.product_status = 'ORDERED') AND
(product_options.opt_name = 'part_no' OR product_options.opt_name = 'stock')
) as t
GROUP BY t.p_id
我得到的是:
+------------------------------------------------------------+
| p_id | product_name | part_no | stock | product_status |
+------------------------------------------------------------+
| 2 | Mouse ABC | MS-ABC-001 | NULL | ORDERED |
| 3 | Monitor ABC | MO-ABC-001 | NULL | ORDERED |
+------------------------------------------------------------+
但是,我想在stock
字段显示空值,因为product\u options
上的数据有:
+------------------------------------------------------------+
| p_id | product_name | part_no | stock | product_status |
+------------------------------------------------------------+
| 2 | Mouse ABC | MS-ABC-001 | 14 | ORDERED |
| 3 | Monitor ABC | MO-ABC-001 | 10 | ORDERED |
+------------------------------------------------------------+
问题是,如何显示/合并两个具有这种大小写的表?
我试着使用GROUP\u CONCAT
,但这不是我要搜索的
看
请提供帮助。尝试以下查询:
select p.p_id p_id , p.product_name product_name ,
(select i.opt_value from product_options i where i.p_id=p.p_id and i.opt_name='part_no') part_no,
(select i.opt_value from product_options i where i.p_id=p.p_id and i.opt_name='stock') stock,
p.product_status product_status
from products p
where p.product_status='ORDERED';
您可以尝试以下方法:
SELECT
p.p_id p_id ,
p.product_name product_name ,
po.opt_value_1 AS part_no,
po.opt_value_2 AS stock,
p.product_status product_status
FROM
products p LEFT JOIN (SELECT po1.p_id,
po1.opt_name AS opt_name_1,
po1.opt_value AS opt_value_1,
po2.opt_name AS opt_name_2,
po2.opt_value AS opt_value_2
FROM product_options po1
LEFT JOIN product_options po2
ON po1.p_id = po2.p_id
AND po1.opt_name != po2.opt_name
GROUP BY po1.p_id) AS po
ON p.p_id = po.p_id
WHERE p.product_status='ORDERED';
这是你的电话号码
或者,更快,但更多的打字
SELECT p.p_id
, p.product_name
, o1.opt_value part_no
, o2.opt_value stock
, p.product_status
FROM products p
LEFT
JOIN product_options o1
ON o1.p_id = p.p_id
AND o1.opt_name = 'part_no'
LEFT
JOIN product_options o2
ON o2.p_id = p.p_id
AND o2.opt_name = 'stock'
WHERE product_status = 'ordered'
您可以按如下方式将两个查询联接在一起以获得结果表:
SELECT t1.p_id, t1.product_name, t1.part_no, t2.stock, t1.product_status
FROM
(
SELECT products.p_id, products.product_name, products.product_status, po1.opt_value AS 'part_no'
FROM products INNER JOIN product_options AS po1
ON products.p_id = po1.p_id
WHERE po1.opt_name = 'part_no'
) AS t1
INNER JOIN
(
SELECT products.p_id, po2.opt_value AS 'stock'
FROM products INNER JOIN product_options AS po2
ON products.p_id = po2.p_id
WHERE po2.opt_name = 'stock'
) AS t2
ON t1.p_id = t2.p_id;
第一个SELECT
(t1
)通过将product\u options
中的产品仅限于opt\u name
为零件号的产品来获取每个产品的零件号。第二个SELECT
(t2
)使用类似的策略获取股票。将“股票”放在单独的表中可能会有所帮助。然后你就可以加入了。i、 e.将其创建为子查询并加入其中。这不是最有效的方法,但可以做你想做的事情。@RyanVincent是的,子查询就像魅力一样有效。下次我会这样做的。非常感谢。