Search notes:

Column constraint_type (DBA_CONSTRAINTS, ALL_CONSTRAINTS, USER_CONSTRAINTS)

select
  -- count(*),
  constraint_type
from
  dba_constraints
group by
  constraint_type
order by
  count(*) desc;
-- C
-- P
-- R
-- O
-- U
-- F
-- V

Github repository oracle-patterns, path: /Installed/data-dictionary/constraints/constraint_type.sql

The constraint type is a one letter flag which is one of (as of 12cR1):

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

Fatal error: Uncaught PDOException: SQLSTATE[HY000]: General error: 8 attempt to write a readonly database in /home/httpd/vhosts/renenyffenegger.ch/php/web-request-database.php:78 Stack trace: #0 /home/httpd/vhosts/renenyffenegger.ch/php/web-request-database.php(78): PDOStatement->execute(Array) #1 /home/httpd/vhosts/renenyffenegger.ch/php/web-request-database.php(30): insert_webrequest_('/notes/developm...', 1748150012, '216.73.216.65', 'Mozilla/5.0 App...', NULL) #2 /home/httpd/vhosts/renenyffenegger.ch/httpsdocs/notes/development/databases/Oracle/installed/data-dictionary/constraints/constraint_type(71): insert_webrequest() #3 {main} thrown in /home/httpd/vhosts/renenyffenegger.ch/php/web-request-database.php on line 78

Column constraint_type (DBA_CONSTRAINTS, ALL_CONSTRAINTS, USER_CONSTRAINTS)

See also