我有一個帶有以下架構的表徽章
create table badges (
id, serial primary key,
title, text not null,
next_badge_id: int references badges,
.
.
)
給定表為：
id | title | next_badge_id
---- ------------------ ---------------
1 | Bronze Partner | 2
2 | Silver partner | 3
3 | Gold partner | 4
4 | Diamond partner | 5
5 | Platinum partner |
我如何撰寫一個查詢來回傳這個：
id | title | next_badge
---- ------------------ ---------------
1 | Bronze Partner | Silver partner
2 | Silver partner | Gold partner
3 | Gold partner | Diamond partner
4 | Diamond partner | Platinum partner
5 | Platinum partner |
uj5u.com熱心網友回復：
您可以使用left join查詢
示例資料和查詢結構：dbfiddle
select
b1.id,
b1.title,
b2.title as next_badge
from
badges b1
left join badges b2 on b1.next_badge_id = b2.id
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