una - quitar unique oracle

¿Qué significan los códigos de letra en la columna constraint_type de la tabla de user_contraints de Oracle?

Question

select distinct constraint_type from user_constraints;
C
-
C
P
R
U

Parece que P significa clave principal y R significa clave externa, ¿correcto? ¿Qué son U y C?

Answer 1

De la documentación 12cR1 :

C - Check constraint on a table
P - Primary key
U - Unique key
R - Referential integrity
V - With check option, on a view
O - With read only, on a view
H - Hash expression
F - Constraint that involves a REF column
S - Supplemental logging

Answer 2

Code Description Acts On Level
---------------------------------------------
C Check on a table Column
O Read Only on a view Object
P Primary Key Object
R Referential (Foreign Key) Column
U Unique Key Column
V Check Option on a view Object