What do the letter codes in Oracle user_contraints table's constraint_type column stand for?

constraints, oracle, oracleinternals

Solution

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

Problem

``` select distinct constraint_type from user_constraints; C - C P R U ``` Seems P means primary key and R means foreign key, correct? What are U and C?

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