如何在单个 POSTGRESQL 查询中获取列名及其引用类型（即 PRIMARY KEY 和 FOREIGN KEY）？

Question

我提出了以下查询，它为我提供了列名及其数据类型，但没有为我提供引用类型（即该列是 primary_key 还是 foreign_key).

select column_name, data_type,character_maximum_length,is_nullable
from   information_schema.columns
where  table_name ='employee';

这是我得到的输出：

 column_name |     data_type     | character_maximum_length | is_nullable
-------------+-------------------+--------------------------+-------------
 empno       | character varying |                       10 | NO
 full_name   | character varying |                       30 | YES
 city        | character varying |                        9 | YES
 gender      | character         |                        7 | YES

有人可以帮我得到 reference_type（即 PRIMARY_KEY & FOREIGN_KEY ) 以及查询？

Answer 1

你可以试试这个：

 select c.column_name, c.data_type, c.character_maximum_length, c.is_nullable, s.constraint_name, t.constraint_type
    from   information_schema.columns c
    left join information_schema.key_column_usage s on s.table_name = c.table_name and s.column_name = c.column_name
    left join information_schema.table_constraints t on t.table_name = c.table_name and t.constraint_name = s.constraint_name
    where  c.table_name ='employee'

看看这个link https://www.postgresql.org/docs/9.1/static/information-schema.html

如何在单个 POSTGRESQL 查询中获取列名及其引用类型（即 PRIMARY KEY 和 FOREIGN KEY）？

How can I get the column name along with its reference type (i.e PRIMARY KEY & FOREIGN KEY) in a single POSTGRESQL Query?

sql

postgresql

information-schema