sql - SQL - Postgres 字符串 agg 给出重复项
问题描述
我试图从系统表中收集外键映射。我在下面的查询中使用了这个。
查询1:
select
kcu.table_schema,
kcu.table_name as foreign_table,
string_agg(kcu.column_name, ', ') as fk_columns,
rel_tco.table_name as primary_table,
kcu.constraint_name
from
information_schema.table_constraints tco
join information_schema.key_column_usage kcu on
tco.constraint_schema = kcu.constraint_schema
and tco.constraint_name = kcu.constraint_name
join information_schema.referential_constraints rco on
tco.constraint_schema = rco.constraint_schema
and tco.constraint_name = rco.constraint_name
join information_schema.table_constraints rel_tco on
rco.unique_constraint_schema = rel_tco.constraint_schema
and rco.unique_constraint_name = rel_tco.constraint_name
where
tco.constraint_type = 'FOREIGN KEY'
group by
kcu.table_schema,
kcu.table_name,
rel_tco.table_name,
rel_tco.table_schema,
kcu.constraint_name
order by
kcu.table_schema,
kcu.table_name;
但这不会提供指向 Fk 的主表列。所以我在Stackoverflow上找到了这个查询。
查询 2
SELECT
tc.table_schema,
tc.constraint_name,
tc.table_name,
kcu.column_name,
ccu.table_schema AS foreign_table_schema,
ccu.table_name AS foreign_table_name,
ccu.column_name AS foreign_column_name
FROM
information_schema.table_constraints AS tc
JOIN information_schema.key_column_usage AS kcu
ON tc.constraint_name = kcu.constraint_name
AND tc.table_schema = kcu.table_schema
JOIN information_schema.constraint_column_usage AS ccu
ON ccu.constraint_name = tc.constraint_name
AND ccu.table_schema = tc.table_schema
WHERE tc.constraint_type = 'FOREIGN KEY'
现在这个查询给出了单独的列。假设有一个像 (logid, item) 这样的 FK,那么我会得到两行。我想在我的第一个查询中使用 string_agg,我得到了结果,但它最终重复了。喜欢(logid,项目,logid,项目)
重复查询:
select
kcu.table_schema,
kcu.table_name as foreign_table,
string_agg(kcu.column_name, ', ') as fk_columns,
rel_tco.table_name as primary_table,
kcu.constraint_name,
string_agg(ccu.column_name, ', ') as pk_columns
from
information_schema.table_constraints tco
join information_schema.key_column_usage kcu on
tco.constraint_schema = kcu.constraint_schema
and tco.constraint_name = kcu.constraint_name
join information_schema.referential_constraints rco on
tco.constraint_schema = rco.constraint_schema
and tco.constraint_name = rco.constraint_name
join information_schema.table_constraints rel_tco on
rco.unique_constraint_schema = rel_tco.constraint_schema
and rco.unique_constraint_name = rel_tco.constraint_name
JOIN information_schema.constraint_column_usage AS ccu
ON ccu.constraint_name = tco.constraint_name
where
tco.constraint_type = 'FOREIGN KEY'
group by
kcu.table_schema,
kcu.table_name,
rel_tco.table_name,
rel_tco.table_schema,
kcu.constraint_name
order by
kcu.table_schema,
kcu.table_name;
有人可以帮我解决这个查询吗?
示例 FK:
ALTER TABLE myschema.user ADD CONSTRAINT view_option_fk01 FOREIGN KEY (account_id, user_id) REFERENCES myschema.account(account_id, user_id);
预期的查询输出:
解决方案
用于SELECT DISTINCT...
删除重复项
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