如何发现 PostgreSQL 数据库的结构？

How do I discover the structure of a PostgreSQL database?

提问by Liam

I need to write a script that will output data from a PostgreSQL database that I do not know the structure of. What query will return the names of all tables in a database? And what query will list the names of all columns in a table?

我需要编写一个脚本，该脚本将从我不知道其结构的 PostgreSQL 数据库中输出数据。什么查询会返回数据库中所有表的名称？什么查询会列出表中所有列的名称？

采纳答案by CTT

SELECT table_name 
    FROM information_schema.tables 
WHERE table_type = 'BASE TABLE' 
    AND table_schema NOT IN 
        ('pg_catalog', 'information_schema'); 

SELECT column_name 
    FROM information_schema.columns 
WHERE table_name = 'YourTablesName'; 

This page has some great information on retrieving information from information_schema: http://www.alberton.info/postgresql_meta_info.html

这个页面有一些关于从 information_schema 检索信息的重要信息：http: //www.alberton.info/postgresql_meta_info.html

回答by nad2000

The database query tool psql, part of the PostgreSQL distribution, provides table descriptionfunctionality.

数据库查询工具psql是 PostgreSQL 发行版的一部分，提供表描述功能。

# psql postgres postgres
psql (9.1.0)
Type "help" for help.

postgres=# -- list all tables:
postgres=# \d
           List of relations
 Schema |   Name    | Type  |  Owner   
--------+-----------+-------+----------
 public | my_table  | table | postgres
 public | my_table2 | table | postgres
(2 rows)


postgres=# -- describe table:
postgres=# \d my_table
   Table "public.my_table"
 Column |  Type   | Modifiers 
--------+---------+-----------
 col1   | integer | 
 col2   | text    | 

---

---

The rest of the psqlcommands you can get with \?:

您可以使用的其余psql命令\?：

postgres=#   \?
General
  \copyright             show PostgreSQL usage and distribution terms
  \g [FILE] or ;         execute query (and send results to file or |pipe)
  \h [NAME]              help on syntax of SQL commands, * for all commands
  \q                     quit psql

Query Buffer
  \e [FILE] [LINE]       edit the query buffer (or file) with external editor
  \ef [FUNCNAME [LINE]]  edit function definition with external editor
  \p                     show the contents of the query buffer
  \r                     reset (clear) the query buffer
  \s [FILE]              display history or save it to file
  \w FILE                write query buffer to file

Input/Output
  \copy ...              perform SQL COPY with data stream to the client host
  \echo [STRING]         write string to standard output
  \i FILE                execute commands from file
  \o [FILE]              send all query results to file or |pipe
  \qecho [STRING]        write string to query output stream (see \o)

Informational
  (options: S = show system objects, + = additional detail)
  \d[S+]                 list tables, views, and sequences
  \d[S+]  NAME           describe table, view, sequence, or index
  \da[S]  [PATTERN]      list aggregates
  \db[+]  [PATTERN]      list tablespaces
  \dc[S]  [PATTERN]      list conversions
  \dC     [PATTERN]      list casts
  \dd[S]  [PATTERN]      show comments on objects
  \ddp    [PATTERN]      list default privileges
  \dD[S]  [PATTERN]      list domains
  \det[+] [PATTERN]      list foreign tables
  \des[+] [PATTERN]      list foreign servers
  \deu[+] [PATTERN]      list user mappings
  \dew[+] [PATTERN]      list foreign-data wrappers
  \df[antw][S+] [PATRN]  list [only agg/normal/trigger/window] functions
  \dF[+]  [PATTERN]      list text search configurations
  \dFd[+] [PATTERN]      list text search dictionaries
  \dFp[+] [PATTERN]      list text search parsers
  \dFt[+] [PATTERN]      list text search templates
  \dg[+]  [PATTERN]      list roles
  \di[S+] [PATTERN]      list indexes
  \dl                    list large objects, same as \lo_list
  \dL[S+] [PATTERN]      list procedural languages
  \dn[S+] [PATTERN]      list schemas
  \do[S]  [PATTERN]      list operators
  \dO[S+] [PATTERN]      list collations
  \dp     [PATTERN]      list table, view, and sequence access privileges
  \drds [PATRN1 [PATRN2]] list per-database role settings
  \ds[S+] [PATTERN]      list sequences
  \dt[S+] [PATTERN]      list tables
  \dT[S+] [PATTERN]      list data types
  \du[+]  [PATTERN]      list roles
  \dv[S+] [PATTERN]      list views
  \dE[S+] [PATTERN]      list foreign tables
  \dx[+]  [PATTERN]      list extensions
  \l[+]                  list all databases
  \sf[+] FUNCNAME        show a function's definition
  \z      [PATTERN]      same as \dp

Formatting
  \a                     toggle between unaligned and aligned output mode
  \C [STRING]            set table title, or unset if none
  \f [STRING]            show or set field separator for unaligned query output
  \H                     toggle HTML output mode (currently off)
  \pset NAME [VALUE]     set table output option
                         (NAME := {format|border|expanded|fieldsep|footer|null|
                         numericlocale|recordsep|tuples_only|title|tableattr|pager})
  \t [on|off]            show only rows (currently off)
  \T [STRING]            set HTML <table> tag attributes, or unset if none
  \x [on|off]            toggle expanded output (currently off)

Connection
  \c[onnect] [DBNAME|- USER|- HOST|- PORT|-]
                         connect to new database (currently "postgres")
  \encoding [ENCODING]   show or set client encoding
  \password [USERNAME]   securely change the password for a user
  \conninfo              display information about current connection

Operating System
  \cd [DIR]              change the current working directory
  \timing [on|off]       toggle timing of commands (currently off)
  \! [COMMAND]           execute command in shell or start interactive shell

Variables
  \prompt [TEXT] NAME    prompt user to set internal variable
  \set [NAME [VALUE]]    set internal variable, or list all if no parameters
  \unset NAME            unset (delete) internal variable

Large Objects
  \lo_export LOBOID FILE
  \lo_import FILE [COMMENT]
  \lo_list
  \lo_unlink LOBOID      large object operations

回答by SQLMenace

use the ANSI information_schema views

使用 ANSI information_schema 视图

select * from information_schema.tables

select * from information_schema.columns

回答by David

I know this is 5 years after the thread was started, but I'd like to add a slight variation to the solutions proposed so far, in case it helps someone else (ultimately, this is what I had to come up with).

我知道这是该线程启动 5 年后，但我想对迄今为止提出的解决方案添加一些细微的变化，以防它对其他人有所帮助（最终，这是我必须提出的）。

The potential problem with the above, is that if implemented naively against a database with hundreds of tables and thousands of fields, a developer might first query the set of tables, and then inside a loop, query all fields for each table. That hammers the database server. I know nobody specifically suggested using a loop, but nobody warned against it either. And frankly, it's sort of implicit in the way the answers are structured, in that they effectively say "first query all tables, next query all fields". Translated to code, that process can't really be anything other than a loop.

上面的潜在问题是，如果对具有数百个表和数千个字段的数据库进行天真地实现，开发人员可能首先查询表集，然后在循环中查询每个表的所有字段。这打击了数据库服务器。我知道没有人特别建议使用循环，但也没有人警告过它。坦率地说，答案的结构方式有点隐含，因为它们实际上是说“首先查询所有表，然后查询所有字段”。转换为代码，该过程实际上只能是循环。

A better way (imo) to accomplish the original question is to run a query like:

完成原始问题的更好方法 (imo) 是运行如下查询：

SELECT table_schema, table_name, column_name 
    FROM information_schema.columns 
WHERE table_schema in ('a', 'b', 'c', 'd')

where a,b,c,d, ... are the schemas with tables that you care to articulate.

其中 a,b,c,d, ... 是您需要表达的表的模式。

This provides you a dataset that isn't normalized, but that doesn't really matter since you're consuming it with an app anyway - it's trivial to parse the result at the app layer the way you need, and you've only hit the database server with one super lightweight query, instead of possibly hundreds inside a loop.

这为您提供了一个未规范化的数据集，但这并不重要，因为无论如何您都在使用应用程序使用它 - 按照您需要的方式在应用程序层解析结果是微不足道的，而且您只是点击了具有一个超轻量级查询的数据库服务器，而不是一个循环中可能有数百个查询。

Anyway, hope that helps someone!

无论如何，希望对某人有所帮助！

回答by vartec

If you have access to psql, you can use \dand \d table. In terms of SQL, first is equivalent to

如果您有权访问psql，则可以使用\d和\d table。在SQL方面，first相当于

SELECT table_name FROM information_schema.tables WHERE table_schema = 'public'

second

第二

SELECT column_name FROM information_schema.columns WHERE table_name ='table'

回答by madflow

psqlhas the -E, --echo-hiddenoption, which will print out all queries made by psqlcommands.

psql有-E, --echo-hidden选项，它将打印出psql命令所做的所有查询。

For example:

例如：

psql -h localhost -U postgres -p 5432 postgres -E

psql -h localhost -U postgres -p 5432 postgres -E

postgres=# \d
******** QUERY *********
SELECT n.nspname as "Schema",
  c.relname as "Name",
  CASE c.relkind WHEN 'r' THEN 'table' WHEN 'v' THEN 'view' WHEN 'm' THEN 'materialized view' WHEN 'i' THEN 'index' WHEN 'S' THEN 'sequence' WHEN 's' THEN 'special' WHEN 'f' THEN 'foreign table' WHEN 'p' THEN 'table' WHEN 'I' THEN 'index' END as "Type",
  pg_catalog.pg_get_userbyid(c.relowner) as "Owner"
FROM pg_catalog.pg_class c
     LEFT JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace
WHERE c.relkind IN ('r','p','v','m','S','f','')
      AND n.nspname <> 'pg_catalog'
      AND n.nspname <> 'information_schema'
      AND n.nspname !~ '^pg_toast'
  AND pg_catalog.pg_table_is_visible(c.oid)
ORDER BY 1,2;
**************************

回答by Amit Juneja

\d <table_name>

example :

例子 ：

\d authors

回答by Tometzky

Don't write it yourself. Use phpPgAdmin- it will be much easier, faster and less error prone.

不要自己写。使用phpPgAdmin- 它会更容易、更快并且更不容易出错。