Updating multiple rows using join condition

Question

Hi All,
CREATE OR REPLACE
PROCEDURE update_t
IS
BEGIN
FOR emp_rec IN (SELECT EMPLOYEE_ID,FIRST_NAME,LAST_NAME FROM hr.employees)
LOOP
UPDATE
hr.employees1
SET
FIRST_LAST= (
select concat(FIRST_NAME,LAST_NAME) from hr.employees where emp_rec.EMPLOYEE_ID=197);
END LOOP;
END update_t;
I am trying to update first_last column in employees1 table. when i execute this procedure , i am getting the error
Error report:
ORA-01427: single-row subquery returns more than one row
ORA-06512: at "SYSTEM.UPDATE_T", line 13
ORA-06512: at line 1
01427. 00000 - "single-row subquery returns more than one row"
Please let me know a solution for this.
Thanks,
Manikandan

Answer 1

Hello Manikandan,
in your inner SQL the resultset is not restricted to give just one row.
Try this
UPDATE hr.employees1 SET
FIRST_LAST= (select concat(FIRST_NAME,LAST_NAME) from hr.employees where emp_rec.EMPLOYEE_ID=hr.employees.employee_id);Your version did not have any restriction on the rows selected from hr.employees. You gave a where condition that is unrelated to the query.
The best solution for your problem is to avoid the PL/SQL loop completely. You could try something like this:
update
   (select
       e1.first_last,
       e.first_name,
       e.last_name
    from
       hr.employees1 e1,
       hr.employees e
    where
       e1.employee_id=e.employee_id) set
   first_last=first_name||last_name;But beware, updates on joins just work under some restrictions. The key of the table to be updated must be the key of the join. (key preserved is the word to look up.)
Hope that helps,
dhalek