Updating multiple records without having to use a cursor

Question

I am trying to update multiple records in a table.
Eg
Table A -20 records
Table B -10 records.
Would like to update Table B with the updated records in Table A for those records which the primary key matches
and I dont want to use cursors. Is this possible??
Thanx in Advance.

Answer 1

Please refer to the test below, it should give you the general idea,SQL> desc tableA;
Name                            Null?    Type
SEQ                                      NUMBER
INV                                      VARCHAR2(20)
AMT                                      NUMBER(12,2)
AMT2                                     NUMBER(12,2)
SQL> desc tableB;
Name                            Null?    Type
SEQ                                      NUMBER
INV                                      VARCHAR2(20)
AMT                                      NUMBER(12,2)
AMT2                                     NUMBER(12,2)
SQL> select count(*) from tableA;
  COUNT(*)
         6
SQL> select count(*) from tableB;
  COUNT(*)
        12
SQL> UPDATE tableB b
  2  SET b.inv = NVL((SELECT a.inv from tableA a WHERE a.seq = b.seq), b.inv),
  3      b.amt = NVL((SELECT a.amt from tableA a WHERE a.seq = b.seq), b.amt),
  4      b.amt2 = NVL((SELECT a.amt2 from tableA a WHERE a.seq = b.seq), b.amt2)
  5  /
12 rows updated.
*** Please note that this is DIFFERENT from what you asked, here tableB is having more rows, which is fine. We **may not be** able update tableA in this example by reversing the table names, because the join may bring more rows than UPDATE statement needs. ***Thx,
Sri