带有两个表的LEFT OUTER JOIN的GROUP_CONCAT

Question

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

我试图输出这样的东西

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

我尝试使用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

当我添加GROUP_CONCAT和ORDER BY table1.value ，每个值仅列出一个附加信息，但没有列出任何值，并且不会得到重复的附加信息。 我无所事事地移动了订单。

Answer 1

我认为您需要在AdditionalInfo Column而不是table1.value上执行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