Need help with create trigger based on more then 1 table and join.

Question

Hello,
Here i have 3 tables
1. Employee
PERSON_ID
1
1
N
NUMBER
None
ORG_ID
2
N
NUMBER
Frequency
LOC_ID
3
N
NUMBER
Frequency
JOB_ID
4
Y
NUMBER
Height Balanced
FLSA_STATUS_ID
5
Y
NUMBER
Frequency
FULL_NAME
6
N
VARCHAR2 (250 Byte)
Height Balanced
FIRST_NAME
7
N
VARCHAR2 (20 Byte)
Height Balanced
MIDDLE_NAME
8
Y
VARCHAR2 (60 Byte)
Height Balanced
LAST_NAME
9
N
VARCHAR2 (40 Byte)
Height Balanced
PREFERRED_NAME
10
Y
VARCHAR2 (80 Byte)
None
EMAIL
11
Y
VARCHAR2 (250 Byte)
None
MAILSTOP
12
Y
VARCHAR2 (100 Byte)
None
HIRE_DATE
13
N
DATE
None
2. ems_candidate
EMS_CANDIDATE_ID
1
1
N
NUMBER
None
EMS_JOB_ID
2
Y
NUMBER
Frequency
NAME
3
N
VARCHAR2 (255 Byte)
Frequency
EMAIL
4
Y
VARCHAR2 (255 Byte)
None
TELEPHONE
5
Y
VARCHAR2 (25 Byte)
None
EMS_SOURCE_ID
6
Y
NUMBER
Frequency
RECEIVED_DATE
7
Y
DATE
Frequency
COMMENTS
8
Y
VARCHAR2 (4000 Byte)
None
3. employee_resources
EMP_RES_ID
1
1
N
NUMBER
None
PERSON_ID
2
Y
NUMBER
Height Balanced
CANDIDATE_ID
3
Y
NUMBER
Frequency
EMP_START_DATE
4
Y
DATE
None
CUSTOM_RESOURCE_FLAG
5
Y
NUMBER (1)
None
RESOURCE_GROUP_ID
6
N
NUMBER
Frequency
RESOURCE_STATUS_ID
7
N
NUMBER
Frequency
GROUP_LOC_ID
8
N
NUMBER
Height Balanced
ASSIGNED_JIRA
9
Y
VARCHAR2 (250 Byte)
None
REVOKED_JIRA
10
Y
VARCHAR2 (250 Byte)
None
CREATED_DATE
11
Y
DATE
SYSDATE
None
UPDATED_DATE
12
Y
DATE
None
Now i want to create trigger when new record get inserted in employee table wanted to update person_id in employee_resources table.
So i want to match ems_candidate.name with employee.full_name , ems_candidate.ems_job_id with employee.ems_job_id. And if it matched then update person_id in employee_resources table else through an exception and insert record in temp table.
If anybody has an idea can u please help me.
Thanks,
Gayatri.

Answer 1

I created below trigger
CREATE TRIGGER emp_resources_upd_person_id
AFTER INSERT ON ems.employee
FOR EACH ROW
BEGIN
    UPDATE ems.employee_resources
       SET person_id = :new.person_id
     WHERE candidate_id = (SELECT ems_candidate_id  
                             FROM ems.ems_candidate cand, ems.employee emp
                            WHERE TRIM(UPPER(emp.first_name)) = TRIM(UPPER(SUBSTR (cand.name, 1, INSTR (cand.name, ' ') - 1)))
                              AND TRIM(UPPER(emp.last_name)) = TRIM(UPPER(SUBSTR (cand.name,INSTR (cand.name, ' ') + 1,DECODE (INSTR (SUBSTR (cand.name, INSTR (cand.name, ' ') + 1), ' '),0,LENGTH (cand.name),(INSTR (SUBSTR (cand.name, INSTR (cand.name, ' ') + 1), ' ') - 1)))))
                              AND emp.person_id = :new.person_id);
EXCEPTION
  WHEN OTHERS THEN
    INSERT INTO ems.update_person_id_exception(person_id,first_name,last_name,full_name) VALUES(:new.person_id,:new.first_name,:new.last_name,:new.full_name);
END;
Now when i am trying to insert row in ems.employee  table it gives me an error
ORA-04091
table string.string is mutating, trigger/function may not see it
Cause: A trigger (or a user defined plsql function that is referenced in this statement) attempted to look at (or modify) a table that was in the middle of being modified by the statement which fired it.
Action: Rewrite the trigger (or function) so it does not read that table.
Can anybody please help me to come out from these error.
Thanks,
Gayatri.