Postgresql 在Postgres中获取引用表

我有一个外键列表。我想找出这些FK指向的表和实际的键指向的表

我有一张FK的清单，像这样：

columnName0, columnName1, columnName2

外键引用

• columnName0

  references

  table0.idTable0

• columnName1

  references

  table1.idTable1

• columnName2

  references

  table2.idTable2

一些示例表：

表0：

idTable0, PK
name

idTable1, PK
age

idTable2, PK
createdOn

表1：

idTable0, PK
name

idTable1, PK
age

idTable2, PK
createdOn

表2：

idTable0, PK
name

idTable1, PK
age

idTable2, PK
createdOn

示例结果：

| column      | referenced_column | referenced_table |
|-------------|-------------------|------------------|
| columnName0 | idTable0          | table0           |
| columnName1 | idTable1          | table1           |
| columnName2 | idTable2          | table2           |

我正在尝试将我在MySQL中所做的事情翻译为：

SELECT DISTINCT
    COLUMN_NAME AS column,
    REFERENCED_COLUMN_NAME AS referenced_column,
    REFERENCED_TABLE_NAME AS referenced_table
FROM 
    INFORMATION_SCHEMA.KEY_COLUMN_USAGE
WHERE 
    COLUMN_NAME IN (?);

...
    select conname, conrelid::regclass, confrelid::regclass, col, fcol
    from pg_constraint c, 
    lateral unnest(conkey, confkey) u(col, fcol)
    where contype = 'f'   -- foreign keys constraints
...

我将不得不使用直接查询（不幸的是，没有存储过程）。

您可以查询。对于列名，您应该查找。外键可以基于多列，因此

pg_constraint

的

conkey

和

confkey

是数组。您必须取消数组的测试以获得列名列表。例如：

select 
    conrelid::regclass table_name, 
    a1.attname column_name, 
    confrelid::regclass referenced_table, 
    a2.attname referenced_column,
    conname constraint_name
from (
    select conname, conrelid::regclass, confrelid::regclass, col, fcol
    from pg_constraint c, 
    lateral unnest(conkey) col, 
    lateral unnest(confkey) fcol
    where contype = 'f'   -- foreign keys constraints
    ) s
join pg_attribute a1 on a1.attrelid = conrelid and a1.attnum = col
join pg_attribute a2 on a2.attrelid = confrelid and a2.attnum = fcol;

 table_name | column_name | referenced_table | referenced_column |    constraint_name     
------------+-------------+------------------+-------------------+------------------------
 products   | image_id    | images           | id                | products_image_id_fkey
(1 row)

---

在Postgres 9.4或更高版本中，函数

unnest（）

可能有多个参数，内部查询可能如下所示：

SELECT DISTINCT
    COLUMN_NAME AS column,
    REFERENCED_COLUMN_NAME AS referenced_column,
    REFERENCED_TABLE_NAME AS referenced_table
FROM 
    INFORMATION_SCHEMA.KEY_COLUMN_USAGE
WHERE 
    COLUMN_NAME IN (?);

...
    select conname, conrelid::regclass, confrelid::regclass, col, fcol
    from pg_constraint c, 
    lateral unnest(conkey, confkey) u(col, fcol)
    where contype = 'f'   -- foreign keys constraints
...

---

@MikeSherrill'CatRecall'-是的，是的，看到了吗