Hi,
I am having a problem with a trigger:
I have 2 tables :
Studies:
----------
STUDY_DB_UID NOT NULL NUMBER
NUMBER_OF_STUDY_SERIES NOT NULL NUMBER(38)
MODALITIES_IN_STUDY VARCHAR2(30)
STUDY_DATE DATE
STUDY_TIME DATE

Series:
------------
SERIES_DB_UID NOT NULL NUMBER
STUDY_DB_UID NOT NULL NUMBER
SERIES_NUMBER NUMBER(38)
MODALITY VARCHAR2(16)
SERIES_DATE DATE
SERIES_TIME DATE
NUMBER_OF_SERIES_IMAGES NOT NULL NUMBER(38)

each study can have one or more seeries.
My problem is i am trying to update the STUDIES.MODALITIES_IN_STUDY according to the study's series and the series' SERIES.MODALITY, meaning the MODALITIES_IN_STUDY column is composed of all the study's series modalities.


+--------------+
| Study 1 |
| CT\MR\XS |
+--------------+
/ | \
/ | \
+-----------+ +-----------+ +-----------+
| Series 1 | | Series 2 | | Series 3 |
| CT | | MR | | XS |
+-----------+ +-----------+ +-----------+

I have a trigger after delete for each row that calls a package that performs a select on the SERIES table to fetch all MODALITY for a certain study.
I tried using a simple select, i tried using PL/SQL table but i keep getting ORA-4091 error.

What do i do?
Thanks,
Rotem.