# Versión
SELECT * FROM v$version
# Usuario actual
SELECT user FROM dual
# Listado de esquemas
SELECT owner FROM all_tables GROUP BY owner
# Tablas de un esquema
SELECT table_name FROM all_tables where owner='<schema>' ORDER BY table_name
# Columnas de una tabla
SELECT column_name, data_type FROM all_tab_columns WHERE table_name='<table>'
# Datos de una tabla
SELECT * FROM sys.<table>
SELECT * FROM <schema>.<table>
to_char(dbms_xmlgen.getxml('select "'|| (select substr(banner,0,25) from v$version where rownum=1)||'" from sys.dual'))
UNION SELECT columna1 || ' - ' || columna2 || ' - ' || columna3 FROM tabla1-- -