MySQL的Group_Concat函数错过了空值。如何对包括NULL的行进行分组。

Question

考虑以下Table1的例子

usrID orderID deliverID
1     303     102
1     304     103
2     305     NULL
2     306     105
3     307     NULL
3     308     NULL

我想将orderID，deliverID和group连接为usrID，如下所示

usrID orderID_group deliverID_group
1     303,304       102,103
2     305,306       NULL,105
3     307,308       NULL,NULL

我正在使用以下错误NULL值的MySQL查询。

SELECT usrID,
       GROUP_CONCAT(orderID SEPARATOR “,” ) AS orderID_group,
       GROUP_CONCAT(deliverID SEPARATOR “,”) AS deliverID_group
FROM   table1
GROUP  BY usrID;

我希望按顺序包含NOT NULL和NULL。如果有人友好地编写MySQL查询，我将不胜感激。感谢

Answer 1

尝试

SELECT usrID, 
       GROUP_CONCAT(case when orderID is null then 'null' else orderID end order by orderID) AS orderID_group, 
       GROUP_CONCAT(case when deliverID is null then 'null' else deliverID end order by orderID) AS deliverID_group 
FROM table1 
GROUP BY usrID;