How to populate same value for multiple rows using pl/sql - oracle

Question

How do I populate the same data into multiple rows, if the employee id is the same. Without querying the table every time
E.g.
If I get below rows from the Employee Table
EMPLID CHANGETIME
------ --------------
1234 8/10/2017
1234 8/11/2017
For the above employee I need to query the NAME table to get the names and populate both rows.
EMPLID CHANGETIME FirstNAME LastNAME
------ ---------- --------- --------
1234 08/10/17 JOHN MATHEW
1234 08/11/17 JOHN MATHEW
When I query first time would like to store it in array or some variable and populate the same if EMPLID matches previous one.
Just want to do this to improve performance. Any hint would be helpful.
Right now I'm using bulk insert into type table and it goes and searches the NAME table every time a row is fetched from EMPLOYEE table

Answer 1

I would use a join for getting the employee name (also within pl/sql) like:
SELECT e.emplid, e.first_name, e.last_name, c.changetime
FROM employee_changes c
INNER JOIN employee e ON e.emplid = c.emplid
WHERE c.change_time > sysdate - 30
ORDER BY e.emplid, c.change_time
Select can be used as cursor if you want to ...

Answer 2

I think you need some extra criteria, like "the last change time".
In that case you can code something like this:
SELECT e.EMPLID, e.CHANGETIME, n.FirstNAME, n.LastNAME
FROM Employee e, NAME n
WHERE e.emplid = n.emplid
AND e.changetime = (SELECT MAX(e1.changetime)
FROM Employee e1
WHERE e1.emplid = e.emplid);
"For each Employee, just get de max changetime"

Answer 3

If you are using 11g you should consider using the Result Cache feature. This allows us to define functions whose returned values are stored in memory. Something like this:
create or replace function get_name
(p_empid pls_integer)
return varchar2
result_cache relies_on (names)
is
return_value varchar2(30);
begin
select empname into return_value
from names
where empid = p_empid;
return return_value;
end get_name;
/
Note the RELIES_ON clause: this is option but it makes the point that caching is only useful for slowly changing tables. If there's a lot of churn in the NAMES table Oracle will keep flushing the cache and you won't get much benefit. But at least the results will be correct - something which you can't guarantee with your current approach.
Here is a sample. Ignore the elapsed times, but mark how little effort is required to get the same employee name on the second call:
SQL> set autotrace on
SQL> set timing on
SQL> select get_name(7934) from dual
2 /
GET_NAME(7934)
------------------------------------------------------------------------------------------------------------------------------------------------------
MILLER
Elapsed: 00:00:01.25
Execution Plan
----------------------------------------------------------
Plan hash value: 1388734953
-----------------------------------------------------------------
| Id | Operation | Name | Rows | Cost (%CPU)| Time |
-----------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 2 (0)| 00:00:01 |
| 1 | FAST DUAL | | 1 | 2 (0)| 00:00:01 |
-----------------------------------------------------------------
Statistics
----------------------------------------------------------
842 recursive calls
166 db block gets
1074 consistent gets
44 physical reads
30616 redo size
499 bytes sent via SQL*Net to client
437 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
134 sorts (memory)
0 sorts (disk)
1 rows processed
SQL>
Second call:
SQL> r
1* select get_name(7934) from dual
GET_NAME(7934)
------------------------------------------------------------------------------------------------------------------------------------------------------
MILLER
Elapsed: 00:00:00.13
Execution Plan
----------------------------------------------------------
Plan hash value: 1388734953
-----------------------------------------------------------------
| Id | Operation | Name | Rows | Cost (%CPU)| Time |
-----------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 2 (0)| 00:00:01 |
| 1 | FAST DUAL | | 1 | 2 (0)| 00:00:01 |
-----------------------------------------------------------------
Statistics
----------------------------------------------------------
0 recursive calls
0 db block gets
0 consistent gets
0 physical reads
0 redo size
499 bytes sent via SQL*Net to client
437 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
1 rows processed
SQL>
The documentation has lots on this nifty feature. Find out more.