如何使用psql命令在PostgreSQL中执行Oracle的DESCRIBE TABLE?
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
来源:faqs.org
除了PostgreSQL方式(\d“something”或\dt“table”或\ds“sequence”等)
SQL标准方式,如下所示:
select column_name, data_type, character_maximum_length, column_default, is_nullable
from INFORMATION_SCHEMA.COLUMNS where table_name = '<name of table>';
它受到许多db引擎的支持。
如果您想从查询而不是psql获取它,可以查询目录模式。下面是一个复杂的查询,它可以做到这一点:
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系统目录的强大和灵活性,并将帮助您掌握pg_catalog;-)。请确保更改查询中的%s。第一个是Schema,第二个是表名。
您可以使用此选项:
SELECT attname
FROM pg_attribute,pg_class
WHERE attrelid=pg_class.oid
AND relname='TableName'
AND attstattarget <>0;
除了已经找到的命令行\d+<table_name>之外,还可以使用info_schema.columns使用信息模式查找列数据
SELECT *
FROM info_schema.columns
WHERE table_schema = 'your_schema'
AND table_name = 'your_table'
使用以下SQL语句
SELECT DATA_TYPE
FROM INFORMATION_SCHEMA.COLUMNS
WHERE table_name = 'tbl_name'
AND COLUMN_NAME = 'col_name'
若替换tbl_name和col_name,它将显示您要查找的特定列的数据类型。
您也可以使用以下查询进行检查
Select * from schema_name.table_name limit 0;
示例:我的表有两列名称和pwd。下面是截图。
*使用PG admin3
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 |
/dt是列出数据库中所有表的命令。使用/d命令和/d+,我们可以获得表的详细信息。sysntax将如下所示*/d table_name(或)\d+table_name
这个问题的变体(如其他答案中所解释的)对我很有用。
SELECT
COLUMN_NAME
FROM
information_schema.COLUMNS
WHERE
TABLE_NAME = 'city';
详细描述如下:http://www.postgresqltutorial.com/postgresql-describe-table/
我为get表模式编写了以下脚本。
'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;
在MySQL中,DESCRIBE table_name
在PostgreSQL中,\d table_name
或者,可以使用以下长命令:
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
In postgres\d用于描述表结构。
例如\d schema_name.table_name
该命令将为您提供表的基本信息,如列、类型和修饰符。
如果您想了解更多有关表格使用的信息
\d+ schema_name.table_name
这将为您提供额外的信息,如存储、统计目标和描述
为了改进另一个答案的SQL查询(这太棒了!),这里有一个经过修改的查询。它还包括约束名称、继承信息和数据类型,这些数据类型被划分为其组成部分(类型、长度、精度、比例)。它还过滤掉已删除的列(这些列仍然存在于数据库中)。
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
;
这应该是解决方案:
SELECT * FROM information_schema.columns
WHERE table_schema = 'your_schema'
AND table_name = 'your_table'
1) 使用psql的PostgreSQL描述表
在psql命令行工具中,使用\d table_name或\d+table_name查找表的列信息
2) PostgreSQL使用information_schema描述表
SELECT语句查询information_schema数据库中列表的column_name、数据类型、字符最大长度;
选择列名称、数据类型、字符最大长度来自INFORMATION_SCHEMA.COLUMNS,其中table_name=“tablename”;
有关详细信息https://www.postgresqltutorial.com/postgresql-describe-table/
即使请求了psql命令,我也会添加pg_dump命令。因为它生成了以前的MySQl用户更常见的输出。
#sudo-u postgres pg_dump--table=my_table_name--仅模式mydb
下面的命令可以简单地描述多个表
\dt <table> <table>
下面的命令可以详细描述多个表:
\d <table> <table>
下面的命令可以更详细地描述多个表:
\d+ <table> <table>
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