有一張服務器表， 一張服務器的服務表。
目標是查詢服務器表，并把該服務器上運行的服務進行字串連接作為一個列的值。
server 表（服務器表）
service 表（服務表）
我寫的 sql 陳述句，很爛
select t1. *, t2.service from r_server t1 left join
(select a_id, GROUP_CONCAT(b_n) as "service" from
(SELECT a.id as "a_id", b.id as "b_id", b.name as "b_n" FROM "r_server" a left join "r_serverservice" b on a.id = b.server_id) temp
group by a_id) t2
on t1.id = t2.a_id
查詢的結果
感謝大佬！uj5u.com熱心網友回復：
select t1. *, t2.service from r_server t1 left join
(select a_id, GROUP_CONCAT(b_n) as "service" from
(SELECT a.id as "a_id", b.id as "b_id", b.name as "b_n"
FROM "r_server" a left join "r_serverservice" b on a.id = b.server_id) temp
group by a_id) t2
on t1.id = t2.a_id
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