如何解决我可以将2个Json_agg查询合并为一个结果吗？
我有以下2个查询。我需要使用两个查询，因为第一个查询获取匹配的记录总数，第二个查询返回前50个结果。我想在一个调用中运行两个查询，并将结果合并为一个结果？
如何将这两个结果合并为一个值？我尝试了UNION，但似乎不适用于JSON输出。
我正在使用Postges 11
select count(tbl_310.id)
FROM
schema_1.tbl_310 tbl_310
left join schema_1.tbl_310_customid custom on custom.id=tbl_310.id
left join lateral (
select distinct field_53.*
from schema_1.tbl_310_to_tbl_342_field_53 field_53
where field_53.tbl_310_id=tbl_310.id
limit 50) field_53 on true
left join lateral (
select distinct tbl_342.*
from schema_1.tbl_342_customid tbl_342
where tbl_342.id = field_53.tbl_342_id
limit 50
) tbl_342 on true
left join lateral (
select distinct field_41_join.*
from schema_1.tbl_310_field_41_join field_41_join
where field_41_join.id=tbl_310.id
limit 50) field_41_join on true
left join lateral (
select distinct field_41.*
from schema_1.tbl_310_field_41 field_41
where field_41.optionid = field_41_join.optionid
limit 5
) field_41 on true left join lateral (
select distinct field_52_join.*
from schema_1.tbl_310_field_52_join field_52_join
where field_52_join.id=tbl_310.id
limit 50) field_52_join on true
left join lateral (
select distinct field_52.*
from schema_1.tbl_310_field_52 field_52
where field_52.optionid = field_52_join.optionid
limit 5
) field_52 on true
WHERE
field_52.optionid = ANY (Array[1]) ;
select array_to_json(array_agg(t)) from (
select
tbl_310.id,custom.fullname as "CustomID",tbl_310.field_42,tbl_310.field_16,tbl_310.field_1,tbl_310.field_2,tbl_310.field_44,tbl_310.field_8,tbl_310.field_45,tbl_310.id,jsonb_agg(distinct jsonb_build_object('id',tbl_342.id,'data',tbl_342.fullname)) as field_53,jsonb_agg(distinct jsonb_build_object('optionid',field_41.optionid,field_41.option,'attributes',field_41.attributes)) as field_41,field_52.optionid,field_52.option,field_52.attributes)) as field_52
FROM
schema_1.tbl_310 tbl_310
left join schema_1.tbl_310_customid custom on custom.id=tbl_310.id
left join lateral (
select distinct field_53.*
from schema_1.tbl_310_to_tbl_342_field_53 field_53
where field_53.tbl_310_id=tbl_310.id
limit 50) field_53 on true
left join lateral (
select distinct tbl_342.*
from schema_1.tbl_342_customid tbl_342
where tbl_342.id = field_53.tbl_342_id
limit 50
) tbl_342 on true
left join lateral (
select distinct field_41_join.*
from schema_1.tbl_310_field_41_join field_41_join
where field_41_join.id=tbl_310.id
limit 50) field_41_join on true
left join lateral (
select distinct field_41.*
from schema_1.tbl_310_field_41 field_41
where field_41.optionid = field_41_join.optionid
limit 5
) field_41 on true left join lateral (
select distinct field_52_join.*
from schema_1.tbl_310_field_52_join field_52_join
where field_52_join.id=tbl_310.id
limit 50) field_52_join on true
left join lateral (
select distinct field_52.*
from schema_1.tbl_310_field_52 field_52
where field_52.optionid = field_52_join.optionid
limit 5
) field_52 on true
WHERE
field_52.optionid = ANY (Array[1])
GROUP BY tbl_310.id,custom.fullname,tbl_310.id
ORDER BY tbl_310.id asc
Limit 50
) t;
已更新尝试使用您的格式，但出现语法错误。 在这里看到任何问题吗？
SELECT
count(tbl_310.id) AS count,array_to_json((array_agg(t))[1:50]) AS array
FROM
select
tbl_310.id,field_52.attributes)) as field_52
FROM
schema_1.tbl_310 tbl_310
left join schema_1.tbl_310_customid custom on custom.id=tbl_310.id
left join lateral (
select distinct field_53.*
from schema_1.tbl_310_to_tbl_342_field_53 field_53
where field_53.tbl_310_id=tbl_310.id
limit 50) field_53 on true
left join lateral (
select distinct tbl_342.*
from schema_1.tbl_342_customid tbl_342
where tbl_342.id = field_53.tbl_342_id
limit 50
) tbl_342 on true
left join lateral (
select distinct field_41_join.*
from schema_1.tbl_310_field_41_join field_41_join
where field_41_join.id=tbl_310.id
limit 50) field_41_join on true
left join lateral (
select distinct field_41.*
from schema_1.tbl_310_field_41 field_41
where field_41.optionid = field_41_join.optionid
limit 5
) field_41 on true left join lateral (
select distinct field_52_join.*
from schema_1.tbl_310_field_52_join field_52_join
where field_52_join.id=tbl_310.id
limit 50) field_52_join on true
left join lateral (
select distinct field_52.*
from schema_1.tbl_310_field_52 field_52
where field_52.optionid = field_52_join.optionid
limit 5
) field_52 on true
WHERE
field_52.optionid = ANY (Array[1])
GROUP BY tbl_310.id,tbl_310.id
ORDER BY tbl_310.id asc
) t
解决方法
CTE可以帮助您
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或者，您可以使用已经构建的数组：
WITH (… long and complicated query …) AS intermediate
SELECT
(SELECT count(*) FROM intermediate) AS count,(SELECT json_agg(t) FROM intermediate t LIMIT 50) AS array;
它甚至可能不需要CTE语法，而只是一个子查询，甚至只是
WITH (SELECT array_agg(t) AS arr FROM (… long and complicated query …) t) AS intermediate
SELECT
array_length(arr,1) AS count,array_to_json(arr[1:50]) AS array
FROM intermediate;
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