Question

不确定该怎么称呼，-我确定必须在其他地方询问。

请考虑以下内容，例如

CREATE TABLE abbrv (
    abbrv_id int unsigned primary key not null auto_increment,
    usps_primary varchar(64) not null,
    usps_preferred varchar(16) not null
);

CREATE TABLE abbrv_variation (
    variation_id int unsigned primary key not null auto_increment,
    abbrv_id int unsigned, -- FK
    variation varchar(64) not null
);

INSERT INTO abbrv(usps_primary, usps_preferred) VALUES('North', 'N');
INSERT INTO abbrv(usps_primary, usps_preferred) VALUES('South', 'S');
INSERT INTO abbrv(usps_primary, usps_preferred) VALUES('East', 'E');
INSERT INTO abbrv(usps_primary, usps_preferred) VALUES('West', 'W');

INSERT INTO `abbrv` (usps_primary, usps_preferred) values('ALLEY', 'ALY');
SET @abbrvId = LAST_INSERT_ID();
INSERT INTO `abbrv_variation` (abbrv_id, variation) VALUES(@abbrvId, 'ALLEE');
INSERT INTO `abbrv_variation` (abbrv_id, variation) VALUES(@abbrvId, 'ALLY');

INSERT INTO `abbrv` (usps_primary, usps_preferred) values('ANEX', 'ANX');
SET @abbrvId = LAST_INSERT_ID();
INSERT INTO `abbrv_variation` (abbrv_id, variation) VALUES(@abbrvId, 'ANNEX');
INSERT INTO `abbrv_variation` (abbrv_id, variation) VALUES(@abbrvId, 'ANNX');
INSERT INTO `abbrv_variation` (abbrv_id, variation) VALUES(@abbrvId, 'ANX');

我只是想做的是返回诸如以下内容：

+--------------+----------------+-----------+
| usps_primary | usps_preferred | variation |
+--------------+----------------+-----------+
| North        | N              | North     | <-- 1 row for "usps_primary"
| North        | N              | N         | <-- 1 row for "usps_preferred"
| South        | S              | South     | <-- 1 row for "usps_primary"
| South        | S              | S         | <-- 1 row for "usps_preferred"
| East         | E              | East      | <-- 1 row for "usps_primary"
| East         | E              | E         | <-- 1 row for "usps_preferred"
| West         | W              | West      | <-- 1 row for "usps_primary"
| West         | W              | W         | <-- 1 row for "usps_preferred"
| ALLEY        | ALY            | ALLEY     | <-- 1 row for "usps_primary"
| ALLEY        | ALY            | ALY       | <-- 1 row for "usps_preferred"
| ALLEY        | ALY            | ALLEE     | X-- one row for each 
| ALLEY        | ALY            | ALLY      | X-- variation    
| ANEX         | ANX            | ANEX      | <-- 1 row for "usps_primary"
| ANEX         | ANX            | ANX       | <-- 1 row for "usps_preferred"
| ANEX         | ANX            | ANNEX     | X-- one row for each 
| ANEX         | ANX            | ANNX      | X-- variation

排序并不重要-只是它们都在那里。最初，此表仅具有每个表的“变体”行，但由于它是一个非常大的表，可确保每次添加新变体时都输入所有这些行，因此变得难以维护。

我当然尝试了一个简单的LEFT JOIN，CROSS JOIN，OUTER JOIN，左右连接一些-我真的不知道这里合适的做法是什么。

交叉连接似乎是正确的，但我不希望整个系列赛，每个都只是2倍。

Answer 1

输出：

SELECT usps_primary, usps_preferred, usps_primary AS variation FROM abbrv
UNION
SELECT usps_primary, usps_preferred, usps_preferred FROM abbrv
UNION
SELECT a.usps_primary, a.usps_preferred, v.variation FROM abbrv AS a 
INNER JOIN abbrv_variation AS v USING (abbrv_id)
ORDER BY usps_primary

Answer 2

您可以使用LATERAL：

SELECT usps_primary, usps_preferred, s.variation
FROM abbrv a
,LATERAL(SELECT a.usps_primary AS variation
         UNION SELECT a.usps_preferred 
         UNION SELECT av.variation FROM abbrv_variation av WHERE a.abbrv_id = av.abbrv_id) s

db<>fiddle demo

输出：

+---------------+-----------------+-----------+
| usps_primary  | usps_preferred  | variation |
+---------------+-----------------+-----------+
| North         | N               | North     |
| North         | N               | N         |
| South         | S               | South     |
| South         | S               | S         |
| East          | E               | East      |
| East          | E               | E         |
| West          | W               | West      |
| West          | W               | W         |
| ALLEY         | ALY             | ALLEY     |
| ALLEY         | ALY             | ALY       |
| ALLEY         | ALY             | ALLEE     |
| ALLEY         | ALY             | ALLY      |
| ANEX          | ANX             | ANEX      |
| ANEX          | ANX             | ANX       |
| ANEX          | ANX             | ANNEX     |
| ANEX          | ANX             | ANNX      |
+---------------+-----------------+-----------+

左联接，但父表中有其他行

2 个答案: