帶有兩個表的LEFT OUTER JOIN的GROUP_CONCAT

Question

SELECT table1.value, table2.additionalinfo
FROM table1
LEFT OUTER JOIN table2
ON table1.ID=table2.ID

我試圖輸出這樣的東西

Value   AdditionalInfo
blah    something, somethingelse, more
blah2   NULL
blah3   stuff

但我明白了

Value   AdditionalInfo
blah    something
blah    somethingelse
blah    more
blah2   NULL
blah3   stuff

我嘗試使用GROUP_CONCAT和GROUP_CONCAT(DISTINCT)

SELECT GROUP_CONCAT(table1.value), table2.additionalinfo
FROM table1
left outer JOIN table2
ON table1.ID=table2.ID ORDER BY table1.value

當我添加GROUP_CONCAT和ORDER BY table1.value ，每個值僅列出一個附加信息，但沒有列出任何值，並且不會得到重復的附加信息。 我無所事事地移動了訂單。

Answer 1

我認為您需要在AdditionalInfo Column而不是table1.value上執行GROUP_CONCAT

SELECT table1.value, 
GROUP_CONCAT(distinct table2.additionalinfo) additionalinfo
FROM table1
left outer JOIN table2 ON table1.ID=table2.ID 
GROUP BY table1.value
ORDER BY table1.value