Mohamed Houri’s Oracle Notes

March 21, 2013

ORA-02431: Cannot disable constraint

Filed under: Trouble shooting — hourim @ 7:21 pm

Recently a question came up on the otn forum which reminded me to write a small blog article that I will be referring to instead of creating a different test each time I see people asking how to trouble shoot the same error as that mentioned by the Original Poster(OP). The OP was struggling about an existing constraint which, despite he is seeing it via a select against user_constraints table, he, nevertheless, was unable to disable it because of ORA-02431 error: cannot disable constraint FK_Batch_Products no such constraint.
Here below is the select against the OP user_constraints table:

--------------------------- ------------------ -----------
FK_Product_SourceSpecies    R                  ENABLED
FK_Product_CreatePerson     R                  ENABLED
FK_Product_ModifyPerson     R                  ENABLED
FK_Product_ExpressionSystem R                  ENABLED
FK_Product_Localisation     R                  ENABLED
FK_Batch_Products           R                  ENABLED

Have you already spotted the obvious?

Well if not then let me tell you one thing:  each time I see lowercase letters in an Oracle object names then I am hundred percent sure that the owner of this object will have trouble identifying those objects and I will not be surprised when he will be faced to such a kind of non existing object error.

Below I have modeled the problem and have shown the solution to the OP.

SQL> create table t (id number, vc varchar2(10));

Table created.

SQL> alter table t add constraint t_pk primary key (id);

Table altered.

SQL> alter table t add constraint "t_lower_case" check (vc != 'NONE');

Table altered.

SQL> select table_name, constraint_name
  2  from user_constraints
  3  where table_name = 'T';

TABLE_NAME                     CONSTRAINT_NAME
------------------------------ ------------------------------
T                              T_PK
T                              t_lower_case

SQL> alter table t drop constraint t_lower_case;
alter table t drop constraint t_lower_case
ERROR at line 1:
ORA-02443: Cannot drop constraint  - nonexistent constraint

SQL> alter table t drop constraint "t_lower_case";

Table altered.

Bottom Line : it is very important to be careful when creating Oracle objects; give  them correct naming standard without enclosing their names between double quotes i.e. “ “


  1. Mohamed, it may be a tool that did this, rather than the developer himself.
    (Still wrong though). 😉

    Comment by Martin Rose — March 21, 2013 @ 10:11 pm | Reply

  2. Martin,

    Very often, if not always, I forget that “tool” or “ERP’’ automatic generated code. Thanks for spotting that to me


    Comment by Houri — March 22, 2013 @ 7:38 am | Reply

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