Dictionary

Foreign Key

SELECT C.TABLE_NAME||'.'||C.COLUMN_NAME||' = '||
B.TABLE_NAME||'.'||B.COLUMN_NAME ||' AND ' AS JOIN
FROM ALL_CONSTRAINTS A
LEFT JOIN ALL_CONS_COLUMNS B ON A.R_CONSTRAINT_NAME = B.CONSTRAINT_NAME
LEFT JOIN ALL_CONS_COLUMNS C ON A.CONSTRAINT_NAME = C.CONSTRAINT_NAME
WHERE A.TABLE_NAME = 'EMPLOYEES' --TABELA ORIGEM
AND A.CONSTRAINT_TYPE = 'R'; 

Primary Key

SELECT ALL_CONS_COLUMNS.TABLE_NAME TABELA, ALL_CONS_COLUMNS.COLUMN_NAME CHAVE_PRIMARIA
FROM ALL_CONSTRAINTS
JOIN ALL_CONS_COLUMNS ON ALL_CONSTRAINTS.CONSTRAINT_NAME =      ALL_CONS_COLUMNS.CONSTRAINT_NAME
WHERE ALL_CONSTRAINTS.TABLE_NAME  = 'EMPLOYEES'
 AND CONSTRAINT_TYPE = 'P';

Constraints

 SELECT ALL_CONS_COLUMNS.TABLE_NAME TABELA,
 ALL_CONS_COLUMNS.COLUMN_NAME COLUNA, 
 ALL_CONSTRAINTS.SEARCH_CONDITION RESTRICAO
 FROM ALL_CONSTRAINTS
 JOIN ALL_CONS_COLUMNS ON ALL_CONSTRAINTS.CONSTRAINT_NAME = ALL_CONS_COLUMNS.CONSTRAINT_NAME
 WHERE ALL_CONSTRAINTS.TABLE_NAME  = 'EMPLOYEES'
 AND CONSTRAINT_TYE = 'C'; 

Describe

SELECT TABLE_NAME AS TABELA, COLUMN_NAME AS COLUNA,
 DECODE(DATA_TYPE, 'DATE',DATA_TYPE,'NUMBER',DATA_TYPE||DECODE(DATA_SCALE,NULL,NULL,
 '('||DATA_PRECISION||','||DATA_SCALE||')'),
 'VARCHAR2',DATA_TYPE||'('||DATA_LENGTH||')',NULL)
 DATA_TYPE
 FROM USER_TAB_COLUMNS