PostgreSQL“ DESCRIBE TABLE”
-
01-07-2019 - |
题
如何在PostgreSQL中执行Oracle的 DESCRIBE TABLE
(使用psql命令)?
解决方案
其他提示
除了PostgreSQL方式(\ d'thing'或\ dt'table'或\ ds'sequence'等等)
SQL标准方式,如图所示此处:
select column_name, data_type, character_maximum_length
from INFORMATION_SCHEMA.COLUMNS where table_name = '<name of table>';
它受到许多数据库引擎的支持。
如果要从查询而不是psql获取它,可以查询目录模式。这是一个复杂的查询:
SELECT
f.attnum AS number,
f.attname AS name,
f.attnum,
f.attnotnull AS notnull,
pg_catalog.format_type(f.atttypid,f.atttypmod) AS type,
CASE
WHEN p.contype = 'p' THEN 't'
ELSE 'f'
END AS primarykey,
CASE
WHEN p.contype = 'u' THEN 't'
ELSE 'f'
END AS uniquekey,
CASE
WHEN p.contype = 'f' THEN g.relname
END AS foreignkey,
CASE
WHEN p.contype = 'f' THEN p.confkey
END AS foreignkey_fieldnum,
CASE
WHEN p.contype = 'f' THEN g.relname
END AS foreignkey,
CASE
WHEN p.contype = 'f' THEN p.conkey
END AS foreignkey_connnum,
CASE
WHEN f.atthasdef = 't' THEN d.adsrc
END AS default
FROM pg_attribute f
JOIN pg_class c ON c.oid = f.attrelid
JOIN pg_type t ON t.oid = f.atttypid
LEFT JOIN pg_attrdef d ON d.adrelid = c.oid AND d.adnum = f.attnum
LEFT JOIN pg_namespace n ON n.oid = c.relnamespace
LEFT JOIN pg_constraint p ON p.conrelid = c.oid AND f.attnum = ANY (p.conkey)
LEFT JOIN pg_class AS g ON p.confrelid = g.oid
WHERE c.relkind = 'r'::char
AND n.nspname = '%s' -- Replace with Schema name
AND c.relname = '%s' -- Replace with table name
AND f.attnum > 0 ORDER BY number
;
它非常复杂,但它确实向您展示了PostgreSQL系统目录的强大功能和灵活性,并且可以帮助您实现pg_catalog掌握;-)。请务必更改查询中的%s。第一个是Schema,第二个是表名。
您可以使用psql斜杠命令执行此操作:
\d myTable describe table
它也适用于其他对象:
\d myView describe view
\d myIndex describe index
\d mySequence describe sequence
资料来源: faqs.org
DESCRIBE TABLE
的psql等价物是 \ d table
。
有关详细信息,请参阅PostgreSQL手册的psql部分。
您可以使用星号执行 \ d *搜索模式*
,以查找与您感兴趣的搜索模式相匹配的表格。
除了您已找到的命令行 \ d +&lt; table_name&gt;
之外,您还可以使用信息架构,使用 info_schema.columns
SELECT *
FROM info_schema.columns
WHERE table_schema = 'your_schema'
AND table_name = 'your_table'
您可以使用:
SELECT attname
FROM pg_attribute,pg_class
WHERE attrelid=pg_class.oid
AND relname='TableName'
AND attstattarget <>0;
使用以下SQL语句
SELECT DATA_TYPE
FROM INFORMATION_SCHEMA.COLUMNS
WHERE table_name = 'tbl_name'
AND COLUMN_NAME = 'col_name'
如果替换tbl_name和col_name,它会显示您要查找的特定coloumn的数据类型。
这应该是解决方案:
SELECT * FROM information_schema.columns
WHERE table_schema = 'your_schema'
AND table_name = 'your_table'
查询的这种变化(如其他答案中所述)对我有用。
SELECT
COLUMN_NAME
FROM
information_schema.COLUMNS
WHERE
TABLE_NAME = 'city';
这里详细描述: http://www.postgresqltutorial.com/postgresql-describe-table/
在 MySQL 中,DESCRIBE table_name
在 PostgreSQL ,\ d table_name
中或者,你可以使用这个长命令:
SELECT
a.attname AS Field,
t.typname || '(' || a.atttypmod || ')' AS Type,
CASE WHEN a.attnotnull = 't' THEN 'YES' ELSE 'NO' END AS Null,
CASE WHEN r.contype = 'p' THEN 'PRI' ELSE '' END AS Key,
(SELECT substring(pg_catalog.pg_get_expr(d.adbin, d.adrelid), '\'(.*)\'')
FROM
pg_catalog.pg_attrdef d
WHERE
d.adrelid = a.attrelid
AND d.adnum = a.attnum
AND a.atthasdef) AS Default,
'' as Extras
FROM
pg_class c
JOIN pg_attribute a ON a.attrelid = c.oid
JOIN pg_type t ON a.atttypid = t.oid
LEFT JOIN pg_catalog.pg_constraint r ON c.oid = r.conrelid
AND r.conname = a.attname
WHERE
c.relname = 'tablename'
AND a.attnum > 0
ORDER BY a.attnum
要改进其他答案的SQL查询(这很棒!),这里是一个修改过的查询。它还包括约束名称,继承信息以及分解为组成部分(类型,长度,精度,比例)的数据类型。它还会过滤掉已删除的列(数据库中仍存在这些列)。
SELECT
n.nspname as schema,
c.relname as table,
f.attname as column,
f.attnum as column_id,
f.attnotnull as not_null,
f.attislocal not_inherited,
f.attinhcount inheritance_count,
pg_catalog.format_type(f.atttypid,f.atttypmod) AS data_type_full,
t.typname AS data_type_name,
CASE
WHEN f.atttypmod >= 0 AND t.typname <> 'numeric'THEN (f.atttypmod - 4) --first 4 bytes are for storing actual length of data
END AS data_type_length,
CASE
WHEN t.typname = 'numeric' THEN (((f.atttypmod - 4) >> 16) & 65535)
END AS numeric_precision,
CASE
WHEN t.typname = 'numeric' THEN ((f.atttypmod - 4)& 65535 )
END AS numeric_scale,
CASE
WHEN p.contype = 'p' THEN 't'
ELSE 'f'
END AS is_primary_key,
CASE
WHEN p.contype = 'p' THEN p.conname
END AS primary_key_name,
CASE
WHEN p.contype = 'u' THEN 't'
ELSE 'f'
END AS is_unique_key,
CASE
WHEN p.contype = 'u' THEN p.conname
END AS unique_key_name,
CASE
WHEN p.contype = 'f' THEN 't'
ELSE 'f'
END AS is_foreign_key,
CASE
WHEN p.contype = 'f' THEN p.conname
END AS foreignkey_name,
CASE
WHEN p.contype = 'f' THEN p.confkey
END AS foreign_key_columnid,
CASE
WHEN p.contype = 'f' THEN g.relname
END AS foreign_key_table,
CASE
WHEN p.contype = 'f' THEN p.conkey
END AS foreign_key_local_column_id,
CASE
WHEN f.atthasdef = 't' THEN d.adsrc
END AS default_value
FROM pg_attribute f
JOIN pg_class c ON c.oid = f.attrelid
JOIN pg_type t ON t.oid = f.atttypid
LEFT JOIN pg_attrdef d ON d.adrelid = c.oid AND d.adnum = f.attnum
LEFT JOIN pg_namespace n ON n.oid = c.relnamespace
LEFT JOIN pg_constraint p ON p.conrelid = c.oid AND f.attnum = ANY (p.conkey)
LEFT JOIN pg_class AS g ON p.confrelid = g.oid
WHERE c.relkind = 'r'::char
AND f.attisdropped = false
AND n.nspname = '%s' -- Replace with Schema name
AND c.relname = '%s' -- Replace with table name
AND f.attnum > 0
ORDER BY f.attnum
;
描述表格的最佳方式,例如列,类型,列的修饰符等。
\d+ tablename or \d tablename
Use this command
\d table name
like
\d queuerecords
Table "public.queuerecords"
Column | Type | Modifiers
-----------+-----------------------------+-----------
id | uuid | not null
endtime | timestamp without time zone |
payload | text |
queueid | text |
starttime | timestamp without time zone |
status | text |
In postgres \d is used to describe the table structure.
e.g. \d schema_name.table_name;
this command will provide you the basic info of table such as, columns, type and modifiers.
If you want more info about table use
\d+ schema_name.table_name;
this will give you extra info such as, storage, stats target and description
/ dt是commad,它列出了数据库中存在的所有表。使用结果
/ d命令和/ d +我们可以获取表的详细信息。 sysntax就像
* / d table_name(或)\ d + table_name
我为get table schema设计了以下脚本。
'CREATE TABLE ' || 'yourschema.yourtable' || E'\n(\n' ||
array_to_string(
array_agg(
' ' || column_expr
)
, E',\n'
) || E'\n);\n'
from
(
SELECT ' ' || column_name || ' ' || data_type ||
coalesce('(' || character_maximum_length || ')', '') ||
case when is_nullable = 'YES' then ' NULL' else ' NOT NULL' end as column_expr
FROM information_schema.columns
WHERE table_schema || '.' || table_name = 'yourschema.yourtable'
ORDER BY ordinal_position
) column_list;