是否有一种方法使用SQL列出给定表的所有外键?我知道表名/模式,我可以把它插入。
当前回答
SELECT
conrelid::regclass AS table_from,
conname,
pg_get_constraintdef(oid) as condef
FROM pg_catalog.pg_constraint r
也适用于所有约束条件。例如,使用pysql:
其他回答
使用Key所引用的主键的名称并查询information_schema:
select table_name, column_name
from information_schema.key_column_usage
where constraint_name IN (select constraint_name
from information_schema.referential_constraints
where unique_constraint_name = 'TABLE_NAME_pkey')
这里'TABLE_NAME_pkey'是外键引用的主键的名称。
最快的验证直接在bash答案完全基于这个答案
IFS='' read -r -d '' sql_code << EOF_SQL_CODE
SELECT
o.oid
, o.conname AS constraint_name
, (SELECT nspname FROM pg_namespace WHERE oid=m.relnamespace) AS source_schema
, m.relname AS source_table
, (SELECT a.attname FROM pg_attribute a
WHERE a.attrelid = m.oid AND a.attnum = o.conkey[1] AND a.attisdropped = false) AS source_column
, (SELECT nspname FROM pg_namespace
WHERE oid=f.relnamespace) AS target_schema
, f.relname AS target_table
, (SELECT a.attname FROM pg_attribute a
WHERE a.attrelid = f.oid AND a.attnum = o.confkey[1] AND a.attisdropped = false) AS target_column
, ROW_NUMBER () OVER (ORDER BY o.oid) as rowid
FROM pg_constraint o
LEFT JOIN pg_class f ON f.oid = o.confrelid
LEFT JOIN pg_class m ON m.oid = o.conrelid
WHERE 1=1
AND o.contype = 'f'
AND o.conrelid IN (SELECT oid FROM pg_class c WHERE c.relkind = 'r')
EOF_SQL_CODE
psql -d my_db -c "$sql_code"
我创建了一个小工具来查询和比较数据库模式: Dump PostgreSQL数据库模式到文本
有关于FK的信息,但ollyc的回复提供了更多的细节。
SELECT r.conname
,ct.table_name
,pg_catalog.pg_get_constraintdef(r.oid, true) as condef
FROM pg_catalog.pg_constraint r, information_schema.constraint_table_usage ct
WHERE r.contype = 'f'
AND r.conname = ct.constraint_name
ORDER BY 1
注意:在读取约束列时,不要忘记列的顺序!
SELECT conname, attname
FROM pg_catalog.pg_constraint c
JOIN pg_catalog.pg_attribute a ON a.attrelid = c.conrelid AND a.attnum = ANY (c.conkey)
WHERE attrelid = 'schema.table_name'::regclass
ORDER BY conname, array_position(c.conkey, a.attnum)
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