ORA-1779?? (I have unique index defined)

Question

I execute the query:
UPDATE
(select rec.cod_instalacion_marca cod_instal_marca_RECLAMAC, ins.cod_instalacion_marca cod_instal_marca_DIM_INST_MAR
from ods.RECLAMAC rec
INNER JOIN master_dwh.DIM_MODELOS mod ON (rec.cod_modelo = mod.cod_modelo)
INNER JOIN master_dwh.DIM_INSTAL_MARCAS ins ON (rec.taller_implicado = ins.cod_instalacion and mod.cod_marca = ins.cod_marca))
SET cod_instal_marca_RECLAMAC = cod_instal_marca_DIM_INST_MAR
And I received the error:
ORA-01779: cannot modify a column that maps to a non-key preserved column
But I have:
*) Primary key in the field: ins.cod_instalacion_marca (table: master_dwh.DIM_INSTAL_MARCAS)
*) Unique Key in the fields: ins.cod_instalacion + ins.cod_marca (table: master_dwh.DIM_INSTAL_MARCAS).
How can I solve it???
Thanks very much!

Answer 1

I’m sorry,
But the table RECLAMAC is the table I want to modify!!! I can’t define unique key in this field (rec.cod_instalacion_marca ) because is the field that I want to modify and the values could repeat and that is correct.
I read for example the AskTom Followup:
You NEED a primary key/unique constraint on object_id in T1 to ensure that each row in T joins to AT MOST 1 row in T1.
Consider, if T had:
OBJECT_NAME OBJECT_ID
ABC xxxx
and T1 had:
OBJECT_NAME OBJECT_ID
ABC 123
ABC 456
what should be the outcome of:
ADHOC@VOYAGER> update
2 (select t.object_id toid,t1.object_id t1oid
3 from t,t1
4 where t.object_name=t1.object_name
5 and upper(t.object_name)='PRIMARY_SALESFORCE')
6 set toid=t1oid;
should T have 123 or 456 and under what circumstances? Since the outcome of
that update is 100% AMBIGOUS, we do not permit it. We need to ensure key
preserved-ness and do that with a primary key/unique constraint.
You need that index anyway typically for performance.
But my T1 table in the AskTom example is DIM_INSTAL_MARCAS and I have defined the unique key: ins.cod_instalacion + ins.cod_marca
Look at this:
If I create the field cod_marca in the table RECLAMAC and execute this query, it is executed OK!!!!!!
UPDATE
(select rec.cod_instalacion_marca cod_instal_marca_RECLAMAC, ins.cod_instalacion_marca cod_instal_marca_DIM_INST_MAR
from ods_clientes.EXP_RECLAMACIONES_EXPEDIENTES rec
INNER JOIN maestros_dwh.DIM_INSTALACIONES_MARCAS ins ON (rec.taller_implicado = ins.cod_instalacion and rec.cod_marca = ins.cod_marca))
SET cod_instal_marca_RECLAMAC = cod_instal_marca_DIM_INST_MAR
But if I execute:
UPDATE
(select rec.cod_instalacion_marca cod_instal_marca_RECLAMAC, ins.cod_instalacion_marca cod_instal_marca_DIM_INST_MAR
from ods.RECLAMAC rec
INNER JOIN master_dwh.DIM_MODELOS mod ON (rec.cod_modelo = mod.cod_modelo)
INNER JOIN master_dwh.DIM_INSTAL_MARCAS ins ON (rec.taller_implicado = ins.cod_instalacion and mod.cod_marca = ins.cod_marca))
SET cod_instal_marca_RECLAMAC = cod_instal_marca_DIM_INST_MAR
I receive the error ORA-01779: cannot modify a column that maps to a non-key preserved column
I NEED IT...
What unique index I have to create?
Thanks very much!