我有一个postgres表中的数据,如下所示:
Server | Database | Contact
server1 | db1 | contact 1
server1 | db2 | contact 2
server1 | db3 | contact 3
server2 | db1 | contact 4
server2 | db2 | contact 3
但我需要将其转换为以这种格式传递到前端视图:
Server | Database | Contact
server1 | {db1, db2, db3} | {contact1, contact2, contact3}
server2 | {db1, db2} | {contact3, contact4}
对于Server
列中的每个唯一值,我想在SQL查询中的每个其他列中创建一个数组列。到目前为止,我有类似的东西但它似乎没有在Server
列中创建一个数组(为清晰起见,排除了联系人列):
SELECT "table1"."Server"
COALESCE( NULLIF( array
(
select DISTINCT x
FROM unnest( array_agg(DISTINCT "table1"."Server") ) x
WHERE x IS NOT NULL ), '{}' ), '{"No Data"}' ) AS "serverList" ,
COALESCE( NULLIF( array
(
SELECT x
FROM unnest( array_agg(DISTINCT "table1"."Database") ) x
WHERE x IS NOT NULL ), '{}' ), '{"No Data"}' ) AS "databseList"
FROM "table1"
GROUP BY
"table1"."Server"
如何从“服务器”列中的唯一条目中正确创建数组列?
array_agg()
怎么样?
select server, array_agg(database) as databases, array_agg(contact) as contacts
from t
group by server;
如果值必须在数组中是唯一的,请使用distinct
。