\d命令
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格式：
\d [ pattern ]
\d [ pattern ] +
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该命令将显示每个匹配关系（表，视图，索引，序列）的信息，包括对象所有的列，它们的类型，表空间（如果不是默认的）和任何特殊属性（如NOT NULL或默认值等）。与唯一约束相关的索引，规则，约束，触发器也同样会显示出来。如果关系是一个视图，还会显示视图的定义。
1.如果\d命令什么都不带，将列出当前数据库中的所有表。
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sample_db=# \d
List of relations
Schema | Name | Type | Owner
--------+----------------+-------+---------
public | account | table | postgre
public | book | table | postgre
public | customers | table | postgre
public | fruits | table | postgre
...
public | view_t | view | postgre
public | view_t2 | view | postgre
(42 rows)
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2.\d后面跟一个表名，表示显示这个表的结构定义。
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sample_db=# \d tb_dept2
Table "public.tb_dept2"
Column | Type | Modifiers
----------+-----------------------+-----------
id | integer | not null
name | character varying(22) |
location | character varying(50) |
Indexes:
"tb_dept2_pkey" PRIMARY KEY, btree (id)
"tb_dept2_name_key" UNIQUE CONSTRAINT, btree (name)
Referenced by:
TABLE "tb_tmp" CONSTRAINT "fk_emp_dept" FOREIGN KEY (deptid) REFERENCES tb_dept2(id)
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3.\d也可以显示索引信息
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sample_db=# \d tb_dept2_pkey
Index "public.tb_dept2_pkey"
Column | Type | Definition
--------+---------+------------
id | integer | id
primary key, btree, for table "public.tb_dept2"
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4.\d后面可以跟一通配符"*"或"?"
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sample_db=# \d boo?
Table "public.book"
Column | Type | Modifiers
------------------+------------------------+-----------
bookid | integer | not null
bookname | character varying(255) | not null
authors | character varying(255) | not null
info | character varying(255) |
comment | character varying(255) |
year_publication | date | not null
Indexes:
"uniqididx" UNIQUE, btree (bookid)
"bkcmtidx" btree (comment)
"bknameidx" btree (bookname)
sample_db=# \d a*
Table "public.account"
Column | Type | Modifiers
--------+---------------+-----------
id | integer |
name | character(20) |
Triggers:
account_stamp BEFORE INSERT ON account FOR EACH ROW EXECUTE PROCEDURE account_stam()
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5.\d+命令，该命令将显示比\d命令更详细的信息，除了前面介绍的那些，它还会显示任何与表列关联的注释，以及表中出现的ODI。
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sample_db=# \d+ t
Table "public.t"
Column | Type | Modifiers | Storage | Stats target | Description
----------+---------+-----------+---------+--------------+-------------
quantity | integer | | plain | |
price | integer | | plain | |
Has OIDs: no
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6.匹配不同对象类型的\d命令
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如果想只显示匹配的表，可以使用\dt命令
如果想只显示索引，可以使用\di命令
如果想只显示序号，可以使用\ds命令
如果想只显示视图，可以使用\dv命令
如果想只显示函数，可以使用\df命令
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7.如果想显示SQL已执行的时间，可以用\timing命令
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sample_db=# \timing on
Timing is on.
sample_db=# select count(*) from t;
count
-------
1
(1 row)
Time: 0.348 ms
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8.列出所有的schemas可以使用\dn命令
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sample_db=# \dn
List of schemas
Name | Owner
--------+---------
public | postgre
(1 row)
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9.显示所有的表空间可以用\db命令
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sample_db=# \db
List of tablespaces
Name | Owner | Location
------------+---------+----------
pg_default | postgre |
pg_global | postgre |
(2 rows)
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表空间就是对一个目录，放在这个表空间的表，就是把表的数据文件放到这个表空间下。
10.列出数据库所有角色或用户\du或\dg
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sample_db=# \dg
List of roles
Role name | Attributes | Member of
-----------+------------------------------------------------+-----------
bob | | {}
linux78 | | {}
post4 | | {}
post5 | Superuser, Cannot login | {}
post6 | Create DB, Cannot login | {}
post7 | Create role, Cannot login | {}
post8 | Cannot login | {}
postgre | Superuser, Create role, Create DB, Replication | {}
sample_db=# \du
List of roles
Role name | Attributes | Member of
-----------+------------------------------------------------+-----------
bob | | {}
linux78 | | {}
post4 | | {}
post5 | Superuser, Cannot login | {}
post6 | Create DB, Cannot login | {}
post7 | Create role, Cannot login | {}
post8 | Cannot login | {}
postgre | Superuser, Create role, Create DB, Replication | {}
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11.\dp或\z命令用于显示表的权限分配情况
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sample_db=# \dp t
Access privileges
Schema | Name | Type | Access privileges | Column access privileges
--------+------+-------+-------------------+--------------------------
public | t | table | |
(1 row)
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