MySQL - 根據鍵/值查找錶轉換編碼值

Question

我有2個MySQL表。一個包含表單條目，另一個包含要查找的鍵/值對。

其結構如下：

Table 1 : form_123 

id | element_6 | element_7 | element_8 | element_9 
1  1   6    3   6 
2  4   7    2   4 
3  3   3    5   2 


Table 2 : Options 

id | formid | option_id | option_name 
1  123    1   sausages 
2  123    2   bananas 
3  123    3   grapes 
4  123    4   fish 
5  123    5   bread 
6  123    6   buckfast 
7  123    7   foo 
8  123    8   bar 
9  123    9   apples 
10  123   10   oranges 

什麼是最優雅的MySQL查詢提供以下輸出。目的是在可能的情況下，通過單個select語句將表form_123中的鍵/值查找代碼轉換爲查找值。

id | element_6 | element_7 | element_8 | element_9 
1 sausages  buckfast  grapes buckfast 
2  fish  foo   bananas fish 
3  grapes  grapes  bread  bananas 

Answer 1

使用INNER JOIN（S）這樣的期望輸出

SELECT f.id, 
     o6.option_name as element_6, 
     o7.option_name as element_7, 
     o8.option_name as element_8, 
     o9.option_name as element_9 
FROM form_123 f 
INNER JOIN options o6 ON f.element_6 = o6.option_id 
INNER JOIN options o7 ON f.element_7 = o7.option_id 
INNER JOIN options o8 ON f.element_8 = o8.option_id 
INNER JOIN options o9 ON f.element_9 = o9.option_id 
ORDER BY f.id ASC 

sqlfiddle 您的樣本順便說一句，似乎關閉。

輸出

id element_6  element_7  element_8  element_9 
1 sausages  buckfast  grapes   buckfast 
2 fish   foo    bananas   fish 
3 grapes   grapes   bread   bananas 

如果你有更多formid（S）即將到來，你可以添加所有formids 123 這樣

SELECT f.id, 
     o6.option_name as element_6, 
     o7.option_name as element_7, 
     o8.option_name as element_8, 
     o9.option_name as element_9 
FROM form_123 f 
INNER JOIN options o6 ON f.element_6 = o6.option_id 
INNER JOIN options o7 ON f.element_7 = o7.option_id 
INNER JOIN options o8 ON f.element_8 = o8.option_id 
INNER JOIN options o9 ON f.element_9 = o9.option_id 
WHERE o6.formid = 123 
    AND o7.formid = 123 
    AND o8.formid = 123 
    AND o9.formid = 123 
ORDER BY f.id ASC 

，或者你可以只添加和formid = 123這樣的開啓條件下的條件

SELECT f.id, 
     o6.option_name as element_6, 
     o7.option_name as element_7, 
     o8.option_name as element_8, 
     o9.option_name as element_9 
FROM form_123 f 
INNER JOIN options o6 ON f.element_6 = o6.option_id AND o6.formid = 123 
INNER JOIN options o7 ON f.element_7 = o7.option_id AND o7.formid = 123 
INNER JOIN options o8 ON f.element_8 = o8.option_id AND o8.formid = 123 
INNER JOIN options o9 ON f.element_9 = o9.option_id AND o9.formid = 123 
ORDER BY f.id ASC