php - 如何用GROUP_CONCAT查询返回更多一行？

TXNID                PARENT_TXN_ID      ITEM_NAME

5G161631H9141883L                       Merchandise Total
4HD251984H4919123                       Woodworking 101@Fri 04-05-2013 8:00 pm
4LA48638GR031562M                       Woodworking 101@Fri 04-05-2013 8:00 pm
6TU64611FM249252D                       Woodworking 101@Fri 04-05-2013 8:00 pm
7S953179AV7967542                       Woodworking 101@Fri 04-05-2013 8:00 pm
04916720G2800071A                       Woodworking 101@Fri 04-05-2013 8:00 pm
test1               4HD251984H4919123   setet

the above is my data.here is my query.

SELECT ppv1.*,GROUP_CONCAT(ppv2.txn_id SEPARATOR ' <BR>') GC
from paypal_valid ppv1
LEFT JOIN (SELECT txn_id,parent_txn_id from paypal_valid where parent_txn_id!='')
ppv2 ON ppv1.txn_id=ppv2.parent_txn_id
where ppv1.item_name!='Merchandise Total' and ppv1.parent_txn_id=''

这仅返回1行...我认为应该返回5。我只是不确定为什么只返回一行。

最佳答案

尝试使用group by

 SELECT ppv1.*,GROUP_CONCAT(ppv2.txn_id SEPARATOR ' <BR>') GC
 from paypal_valid ppv1
LEFT JOIN (SELECT txn_id,parent_txn_id from paypal_valid where parent_txn_id!='')
 ppv2 ON ppv1.txn_id=ppv2.parent_txn_id
where ppv1.item_name!='Merchandise Total' and ppv1.parent_txn_id=''
group by ppv1.txn_id
                ^^^-------//make sure u have this in your ppv1 table