查询所有的模式名

SELECT DISTINCT object_name FROM ALL_OBJECTS WHERE OBJECT_TYPE = 'SCH'

根据模式名查询表名

SELECT table_name FROM dba_tables WHERE owner = '模式名'

根据模式和表名查询表字段

SELECT COLUMN_NAME FROM all_tab_columns WHERE onwer = '模式名' AND Table_Name = '表名'

查询单个字段值

SELECT '字段名' From '表名'