如何发现PostgreSQL数据库的结构?

数据库查询工具 psql ,是PostgreSQL发行版的一部分,提供 表说明 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    | 

其余的 psql \? :

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

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'; 

http://www.alberton.info/postgresql_meta_info.html

在模式视图中使用ANSI信息

select * from information_schema.tables

select * from information_schema.columns

我知道这是线程启动后的5年,但我想对目前提出的解决方案稍加修改,以防它对其他人有所帮助(最终,这是我必须想到的)。

上面提到的潜在问题是,如果针对具有数百个表和数千个字段的数据库天真地实现,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,答案的结构有点含蓄,因为它们有效地说“首先查询所有表,然后查询所有字段”。翻译成代码后,这个过程实际上只能是一个循环。

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')

其中a,b,c,d。。。是您想要表达的带有表的模式。

这为您提供了一个未规范化的数据集,但这并不重要,因为您使用的是一个应用程序——按照您需要的方式在应用程序层解析结果很简单,而且您只使用一个超轻量查询访问了数据库服务器,而不是循环中的数百个查询。

不管怎样,希望这能帮助别人!

如果您有权访问 \d 和 \d table . 就SQL而言,first相当于

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

第二

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

psql 有 -E, --echo-hidden

例如:

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;
**************************

\d <table_name>

例子:

\d authors

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