How to create stored procedure that returns query result?

Question

I have query that has a lot of columns (about 30) and I would like to place that query in stored procedure. The reason behind that is because this query is used in multiple places in the system. There are situations when I need to pull whole table result set and sometimes I need to look for specific record only (filtered by id). Here is example of the query:

SELECT
    TRIM(t1.rec_id) AS rec_id,
    TRIM(t1.date) AS date,
    TRIM(t1.name) AS name,
    TRIM(t1.address) AS address,
    TRIM(t2.year) AS year,
    CASE 
        WHEN LENGTH(TRIM(t3.percent)) <> 0 THEN CONCAT( ROUND( TRIM(t3.percent) * 100, 2) ,'% Whole' )
        WHEN LENGTH(TRIM(t3.partial)) <> 0 THEN CONCAT( ROUND( TRIM(t3.partial) * 100, 2) ,'% Partial' )
    END AS percent
FROM table1 t1
    LEFT OUTER JOIN table2 t2
        ON TRIM(t1.rec_id) = TRIM(t2.rec_id)
    LEFT OUTER JOIN table3 t3 
        ON TRIM(t1.rec_id) = TRIM(t3.rec_id)

-- Here I would like to add WHERE clause filter
-- If RecID argument is not NULL and is valid then query should filter 
-- and return only one record. If not return all records.

ORDER BY t1.rec_id

Query above usually returns around 500-600 records. It's the main source of my application. In some situations I need all records and sometimes only specific record. So in my comment inside of the code above I explained the situation. The stored procedure should have one argument RecID. If that argument is NULL then stored procedure should return all records and columns. If ti's not NULL then it should look for specific RecID and return that row with all columns. I have done some work in SQL 2008+ where I used stored procedures. I'm wondering if someone can show me an example on how this would work in Oracle? I use Oracle 11g with ColdFusion 10. If someone have good example on how this can be completed please let me know. Thank you!

Answer 1

As of a view I suggested in a comment: as you already have a SELECT statement, it is a matter of a few letters to convert it to a view. Here's an example:

SQL> select d.deptno, d.dname, e.empno, e.ename, e.job, e.sal
  2  from dept d join emp e on e.deptno = d.deptno;

    DEPTNO DNAME               EMPNO ENAME      JOB              SAL
---------- -------------- ---------- ---------- --------- ----------
        10 ACCOUNTING           7839 KING       PRESIDENT       5000
        10 ACCOUNTING           7782 CLARK      MANAGER         2450
        10 ACCOUNTING           7934 MILLER     CLERK           1300
        20 RESEARCH             7902 FORD       ANALYST         3000
        20 RESEARCH             7369 SMITH      CLERK            800
        20 RESEARCH             7566 JONES      MANAGER         2975
        30 SALES                7900 JAMES      CLERK            950
        30 SALES                7844 TURNER     SALESMAN        1500
        30 SALES                7654 MARTIN     SALESMAN        1250
        30 SALES                7521 WARD       SALESMAN        1250
        30 SALES                7499 ALLEN      SALESMAN        1600
        30 SALES                7698 BLAKE      MANAGER         2850

12 rows selected.

SQL>

Convert it to a view:

SQL> create or replace view v_emps as
  2  select d.deptno, d.dname, e.empno, e.ename, e.job, e.sal
  3  from dept d join emp e on e.deptno = d.deptno;

View created.

SQL>

See? Lines 2 and 3 are what you already have.

Now, when you want to select something, you'd use a view instead of the same SELECT statement over and over again. For example:

SQL> select dname, sum(sal) from v_emps group by dname;

DNAME            SUM(SAL)
-------------- ----------
ACCOUNTING           8750
RESEARCH             6775
SALES                9400

SQL> select job, count(*) from v_emps group by job;

JOB         COUNT(*)
--------- ----------
CLERK              3
SALESMAN           4
PRESIDENT          1
MANAGER            3
ANALYST            1

SQL> select ename from v_emps where deptno = 20;

ENAME
----------
SMITH
JONES
FORD

SQL>

Quite simple, isn't it?

A view is nothing but a stored query - it doesn't occupy any space, it always returns current data. True - if it is complex and deals with A LOT of data, it may be slow; but then performance tuning takes place.

I'd suggest you to try it; won't cost much, as you've seen - just a simple create or replace view v_emps ...