mysql、postgresql查询表字所有字段

1、mysql查询表字所有字段

• 第一种：

SHOW FULL COLUMNS FROM table_name;

解释：

Field ：字段名
Type：字段类型
Collation：字符集（mysql 5.0以上有）
Null ：是否可以为NULL
Key：索引（PRI,unique,index)
Default：缺省值
Extra：额外（是否 auto_increment)
Privileges：权限
Comment：备注（mysql 5.0以上有)

• 第二种：

SELECT
	COLUMN_NAME 列名,
	COLUMN_COMMENT 名称,
	COLUMN_TYPE 数据类型,
	DATA_TYPE 字段类型,
	CHARACTER_MAXIMUM_LENGTH 长度,
	IS_NULLABLE 是否必填,
	COLUMN_DEFAULT 描述 
FROM
	INFORMATION_SCHEMA.COLUMNS 
WHERE
	table_schema = 'dbname' 
	AND table_name = 'table'

2、postgresql查看表字段

SELECT a.attnum,
a.attname AS field,
t.typname AS type,
a.attlen AS length,
a.atttypmod AS lengthvar,
a.attnotnull AS notnull,
b.description AS comment
FROM pg_class c,
pg_attribute a
LEFT OUTER JOIN pg_description b ON a.attrelid=b.objoid AND a.attnum = b.objsubid,
pg_type t
WHERE c.relname = 't_uc_login'
and a.attnum > 0
and a.attrelid = c.oid
and a.atttypid = t.oid
ORDER BY a.attnum;