UPDATE statement based on query and return multiple value

Question

Hi everybody,
I have two tables: temp3 and temp
One of them (temp3) should be updated based on the query where clause (id and flag columns).
I run this query but it updates all of the records in the temp3. I want to update only records with 'UPDATED' flag.
update temp3 t3
set (id,name,address) = (select t.id, t.name, t.address from temp t, temp3 t3
where t.id = t3.id and t.flag = 'UPDATED');
Does any body know how I can do it?
I appreciate your help
Thx

Answer 1

Hello
Basically you're missing a where clause on your update statement to restrict rows in t3 to the ones that have a corresponding row in t1.
SQL> select * from dt_test_t1;
        ID NAME                 ADDRESS              ROW_STATUS
         1 Joseph Bloggs        Some street          UPDATED
         1 Joe Bloggs           Old street           OLD
         2 Fredrick Bloggs      New street           UPDATED
         2 Fred Bloggs          Some street          OLD
         3 Robert Bloggs        Better street        UPDATED
         3 Bob Bloggs           Some street          OLD
       100 Barry Bethel         Some street          UPDATED
       200 Giles Brandreth      Some street          UPDATED
8 rows selected.
SQL> select * from dt_test_t3;
        ID NAME                 ADDRESS              ROW_STATUS
         1 Joe Bloggs           Old street
         2 Fred Bloggs          Some street
         3 Bob Bloggs           Some street
         4 Joe Smith            Some street
         5 John Doe             Some street
--this update as it stands does not work as it updates rows to have
--null name and address where there is not a proper matching row in
--t1
SQL> UPDATE
  2     dt_test_t3 t3
  3  SET
  4     (       t3.name,
  5             t3.address,
  6             t3.row_status
  7     ) = (SELECT
  8             t1.name,
  9             t1.address,
10             t1.row_status
11          FROM
12             dt_test_t1 t1
13          WHERE
14             t1.id = t3.id
15          AND
16             t1.row_status = 'UPDATED'
17         );
5 rows updated.
SQL> select * from dt_test_t3;
        ID NAME                 ADDRESS              ROW_STATUS
         1 Joseph Bloggs        Some street          UPDATED
         2 Fredrick Bloggs      New street           UPDATED
         3 Robert Bloggs        Better street        UPDATED
4
5
SQL> rollback;
Rollback complete.
--Now add in the where clause to make sure we're only updating rows in
--t3 that have a corresponding row in t1:
SQL> UPDATE
  2     dt_test_t3 t3
  3  SET
  4     (       t3.name,
  5             t3.address,
  6             t3.row_status
  7     ) = (SELECT
  8             t1.name,
  9             t1.address,
10             t1.row_status
11          FROM
12             dt_test_t1 t1
13          WHERE
14             t1.id = t3.id
15          AND
16             t1.row_status = 'UPDATED'
17         )
18  WHERE
19     EXISTS( SELECT
20                     NULL
21             FROM
22                     dt_test_t1 t1
23             WHERE
24                     t1.id = t3.id
25             AND
26                     t1.row_status = 'UPDATED'
27             );
3 rows updated.
SQL> select * from dt_test_t3;
        ID NAME                 ADDRESS              ROW_STATUS
         1 Joseph Bloggs        Some street          UPDATED
         2 Fredrick Bloggs      New street           UPDATED
         3 Robert Bloggs        Better street        UPDATED
         4 Joe Smith            Some street
         5 John Doe             Some streetHTH
David