MySQL中查询所有数据库名和表名
showdatabases;
select table_name from information_schema.tables where table_schema='database_name' and table_type='base table';
select column_name from information_schema.columns where table_schema='database_name' and table_name='table_name';
select column_name,data_type from information_schema.columns where table_schema='database_name' and table_name='table_name';
select * from sysdatabases;
select * from sysobjects where xtype='U';
xtype='U':表示所有用户表，xtype='S':表示所有系统表。
select name from syscolumns whereid=Object_Id('table_name');
selects c.name,st.name from syscolumns sc,systypes st where sc.xtype=st.xtypeandsc.id in(select id from sysobjects where xtype='U'andname='table_name');
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)
select * from user_tables;
select column_name from user_tab_columns where table_name ='table_name';
selectcolumn_name, data_typefromuser_tab_columnswheretable_name ='table_name';
