查询数据库库名表名字段名

SELECT Name FROM Master..SysDatabases ORDER BY Name

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

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

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';