Add constraint 0ra-02299

Question

Table has many records, some records are also duplicate (vm_no,vm_date)
now I am adding a constraint
SQL> alter table vouchermaster
  2  add constraint un_vm_vd unique (vm_no,vm_date);
add constraint un_vm_vd unique (vm_no,vm_date)
ERROR at line 2:
ORA-02299: cannot validate (UN_VM_VD) - duplicate keys foundFirst time I am using UN_VM_VD constraint name
when I check my table duplicate records
SQL> select vm_no,vm_date from vouchermaster
  2  group by vm_no,vm_date
  3  having count(1) >1;
     VM_NO VM_DATE
         5 18-MAY-10
         7 19-MAY-10
        18 19-MAY-10
        38 24-MAY-10guide me can I add constraint Unique or primary key without data lose with force.

Answer 1

Ahmed wrote:
guide me can I add constraint Unique or primary key without data lose with force.Adding unique or primary key constraint with "force" is not possible when duplicate keys exists. Duplicates must be removed first.
However, it is posssible to add this constraint in disabled state using "disable" keyword:
CREATE TABLE TEST763(
X NUMBER );
INSERT INTO TEST763 VALUES( 2 );
insert into test763 values( 2 );
COMMIT;
ALTER TABLE TEST763
ADD CONSTRAINT P_KEY PRIMARY KEY ( X ) ;
SQL Error: ORA-02437: nie można zweryfikować poprawności (TEST.P_KEY) - naruszenie klucza głównego
02437. 00000 -  "cannot validate (%s.%s) - primary key violated"
*Cause:    attempted to validate a primary key with duplicate values or null
           values.
*Action:   remove the duplicates and null values before enabling a primary
           key.
ALTER TABLE TEST763
ADD CONSTRAINT P_KEY PRIMARY KEY ( X ) DISABLE ;
ALTER TABLE TEST763 succeeded.Duplicates still must be removed before enabling the primary key/unique constraint.
ALTER TABLE TEST763
MODIFY CONSTRAINT P_KEY  ENABLE;
SQL Error: ORA-02437: nie można zweryfikować poprawności (TEST.P_KEY) - naruszenie klucza głównego
02437. 00000 -  "cannot validate (%s.%s) - primary key violated"
*Cause:    attempted to validate a primary key with duplicate values or null
           values.
*Action:   remove the duplicates and null values before enabling a primary
           key.