数据库查询字段的结构和长度

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结构:

select column_name,column_comment,data_type 

from information_schema.columns 

where table_name='查询表名称' and table_schema='数据库名称'
所有的表
select table_name from information_schema.tables where table_schema='数据库名称';
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结构
select a.name 表名,b.name 字段名,c.name 字段类型,c.length 字段长度 from sysobjects a,syscolumns b,systypes c where a.id=b.id 
and a.name='DSE_SYS_DISTRICT' and a.xtype='U' and b.xtype=c.xtype 
所有的表：
select name from sysobjects where xtype='u'

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SELECT b.comments as 注释, a.column_name as 列名, a.data_type || '(' || a.data_length || ')' as 数据类型, 
a.nullable as 是否为空 FROM user_tab_columns a, user_col_comments b WHERE a.TABLE_NAME = '表名' and b.table_name = '表名' 
and a.column_name = b.column_name 
所有的表
select * from user_tables;
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结构：

PRAGMA table_info(‘表名’)
所有的表：
SELECT name FROM sqlite_master WHERE type='table' ORDER BY name;