Mysql的合併多行到一個非空值

Question

我有一個數據結構就像一個表：

+-----------+-----------+-----------+-----------+ 
| member_id | bank_name | bank_ac | ac_holder | 
+-----------+-----------+-----------+-----------+ 
|  14 |   | 012-000 |   | 
|  14 |   | 012-001 |  Andy | 
|  14 | CR Bank | 012-002 |  Jacky | 
+-----------+-----------+-----------+-----------+ 

我需要的是選擇與第一個非空值填充所有列的一個條目。作爲：

+-----------+-----------+-----------+-----------+ 
| member_id | bank_name | bank_ac | ac_holder | 
+-----------+-----------+-----------+-----------+ 
|  14 | CR Bank | 012-000 |  Andy | 
+-----------+-----------+-----------+-----------+ 

我不知道如何開始。有人可以給我建議嗎？

ps：空字段不是NULL，它們是空字符串。 架構提供here

Answer 1

如果數據中包含像'（注null是不一樣的「」）爲空值，你可以使用一些聚集

select member_id, 
min(bank_name) bank_name, 
min(bank_ac) bank_ac, 
min(ac_holder) ac_holder 
from demo 
group by member_id 

DEMO

，那麼你可以把案件條款在聚合函數跳過這些類型值

select member_id, 
min(case when bank_name is not null and bank_name <> '' then bank_name end) bank_name, 
min(case when bank_ac is not null and bank_ac <> '' then bank_ac end) bank_ac, 
min(case when ac_holder is not null and ac_holder <> '' then ac_holder end) ac_holder 
from demo 
group by member_id 

DEMO

您的問題

select member_id, 
substring_index(group_concat(case when bank_name is not null and bank_name <> '' then bank_name end order by your_auto_increment_col asc) ,',',1) bank_name, 
substring_index(group_concat(case when bank_ac is not null and bank_ac <> '' then bank_ac end order by your_auto_increment_col asc) ,',',1) bank_ac, 
substring_index(group_concat(case when ac_holder is not null and ac_holder <> '' then ac_holder end order by your_auto_increment_col asc) ,',',1) ac_holder 
from demo 
group by member_id 

DEMO