问题描述
我有一个customers和name列的postgresql表。{p>
features包含jsonb对象，例如features
我想要得到的是{"featureA": true,"featureB": false,"featureC":true}中的那些键的数组，其中每个features的值都为true，例如：
name我从this post中学到了
name | features
----------|---------------------
customerA | [featureA,featureC]
customerB | [featureB,featureC]
如何获得正确的键，但是如何为我的表SELECT key
FROM jsonb_each()
WHERE value = jsonb 'true'
做到这一点？
类似
customers返回SELECT array_agg(key)
FROM jsonb_each((select features from customers))
WHERE value = jsonb 'true'
。
任何帮助将不胜感激。
解决方法
您正在描述横向连接：
select c.name,x.keys
from customers c
cross join lateral (
select array_agg(x.key) keys
from jsonb_each(c.features) x
where x.value = jsonb 'true'
) x
也可以像这样在select子句中使用jsonb_each()：
select
x.name,json_agg(x.feature_name) as features
from (
select
c.name,row_to_json(jsonb_each(c.features))->>'key' as feature_name,(row_to_json(jsonb_each(c.features))->>'value')::bool as value
from customers c
) as x
where x.value
group by x.name;