查询数据库库名表名字段名

SqlServer

1.查询数据库中的所有数据库名：

 SELECT Name FROM Master..SysDatabases ORDER BY Name

2.查询某个数据库中所有的表名：

 SELECT Name FROM SysObjects Where XType='U' ORDER BY Name

3.查询表结构信息：

  SELECT (case when a.colorder=1 then d.name else null end) 表名,  
  a.colorder 字段序号,a.name 字段名,
  (case when COLUMNPROPERTY( a.id,a.name,'IsIdentity')=1 then '√'else '' end) 标识, 
  (case when (SELECT count(*) FROM sysobjects  
  WHERE (name in (SELECT name FROM sysindexes  
  WHERE (id = a.id) AND (indid in  
  (SELECT indid FROM sysindexkeys  
  WHERE (id = a.id) AND (colid in  
  (SELECT colid FROM syscolumns WHERE (id = a.id) AND (name = a.name)))))))  
 AND (xtype = 'PK'))>0 then '√' else '' end) 主键,b.name 类型,a.length 占用字节数,  
 COLUMNPROPERTY(a.id,a.name,'PRECISION') as 长度,  
 isnull(COLUMNPROPERTY(a.id,a.name,'Scale'),0) as 小数位数,(case when a.isnullable=1 then '√'else '' end) 允许空,  
 isnull(e.text,'') 默认值,isnull(g.[value], ' ') AS [说明]
 FROM  syscolumns a 
 left join systypes b on a.xtype=b.xusertype  
 inner join sysobjects d on a.id=d.id and d.xtype='U' and d.name<>'dtproperties' 
 left join syscomments e on a.cdefault=e.id  
 left join sys.extended_properties g on a.id=g.major_id AND a.colid=g.minor_id
 left join sys.extended_properties f on d.id=f.class and f.minor_id=0
 where b.name is not null
 --WHERE d.name='要查询的表' --如果只查询指定表,加上此条件
 order by a.id,a.colorder

4.查询库中所有表的表名和表的数量：
select o.name,i.rows  from sysobjects o,sysindexes i where o.id=i.id and o.Xtype='U' and i.indid<2 
 

Oracle中查询所有数据库名和表名

查询所有数据库

由于Oralce没有库名,只有表空间,所以Oracle没有提供数据库名称查询支持，只提供了表空间名称查询。

select * from v$tablespace;--查询表空间(需要一定权限)

查询当前数据库中所有表名

select * from user_tables;

查询指定表中的所有字段名

select column_name from user_tab_columns where table_name = 'table_name';

查询指定表中的所有字段名和字段类型

select column_name, data_type from user_tab_columns where table_name = 'table_name';

MySQL中查询所有数据库名和表名

查询所有数据库

show databases;

查询指定数据库中所有表名

select table_name from information_schema.tables where table_schema='database_name' and table_type='base table';

查询指定表中的所有字段名

select column_name from information_schema.columns where table_schema='database_name' and table_name='table_name'

查询指定表中的所有字段名和字段类型

select column_name,data_type from information_schema.columns where table_schema='database_name' and table_name='table_name';