Updating a Table using grouping logic

Question

Hi,
I have a requirement
There is table table_a
create table table_a
code number,
name varchar2(50),
city varchar2(50),
state varchar2(20),
group_id
insert into table_a
values
1,'ABC','A;,'A1');
insert into table_a
values
1,'BCD','A;,'A1');
insert into table_a
values
2,'ABC','A;,'A1');
insert into table_a
values
2,'ABE','A;,'A1');
insert into table_a
values
3,'ABF','A;,'A1');
insert into table_a
values
3,'ABH','A;,'A1');
I need to group the above table values
select code,name,city,dept from table_a
group by code,name,city,state
I need to update the table_a based on the groups above through a cursor
I want to update table_a
update table_a set group_id (based on the group valuse from the cursor)
How to approach for the scenario.Any suggestion for this

Answer 1

Hi,
One last Query based on the Query you have posted:
If  I go with the Updated Query
MERGE INTO  table_a    dst
USING  (
           SELECT    name, city, state
           ,         ROW_NUMBER () OVER (ORDER BY name, city, state)
                         AS group_id
           FROM      table_a
           GROUP BY  name, city, state
       )               src
ON     (    dst.name  || 'x'  = src.name  || 'x'     -- CHANGED
       AND  dst.city  || 'x'  = src.city  || 'x'     -- CHANGED
       AND  dst.state || 'x'  = src.state || 'x'     -- CHANGED
WHEN MATCHED THEN UPDATE
SET    dst.group_id  = src.group_id
Now the Records are updated in the table With Group_id Column based on Grouping Logic thats fine
But if after some couple of days there might be new set of rows.Then How the Group values will be maintained?(The above group can contain new rows also.So how the table_a will be updated if there are already GROUP_ID values for example 1.2,3,4 etc)
SELECT    name, city, state
           ,         ROW_NUMBER () OVER (ORDER BY name, city, state)
                         AS group_id
           FROM      table_a
           GROUP BY  name, city, state