SQL using analytical function

Question

Hi all,
I want an help in creating my SQL query to extract the data described below:
I have one table example test containing data like below:
ID     Desc     Status
1     T1          DEACTIVE
2     T2          ACTIVE
3     T3          SUCCESS
4     T4          DEACTIVE
The thing i want to do is selecting all lines with ACTIVE status in this table but is there is no ACTIVE status, my query will give me the last line with DEACTIVE status.
Can I do this in one query by using analytical function for example, if yes can yiu help me on thaht query.
regards,
Raluce

Answer 1

Hi, Raluce,
Here's one way to do that:
WITH got_r_num AS
    SELECT  deptno, ename, job, hiredate
    ,       ROW_NUMBER () OVER ( PARTITION BY  deptno
                                 ORDER BY      job
                                 ,             hiredate  DESC
                               )  AS r_num
    FROM    scott.emp
    WHERE   job  IN ('ANALYST', 'CLERK')
SELECT     deptno, ename, job, hiredate
FROM       got_r_num
WHERE      job     = 'ANALYST'
OR         r_num   = 1
ORDER BY   deptno
Since I don't have a sample version of your table, I used scott.emp to illustrate.
Output:
    DEPTNO ENAME      JOB       HIREDATE
        10 MILLER     CLERK     23-JAN-82
        20 SCOTT      ANALYST   19-APR-87
        20 FORD       ANALYST   03-DEC-81
        30 JAMES      CLERK     03-DEC-81
This query finds all ANALYSTs in each department, regardless of how many there are.  (Deptno 20 happens to have 2 ANALYSTs.)  If there is no ANALYST in a department, then the most recently hired CLERK is included.  (Deptnos 10 and 30 don't have any ANALYSTs.)
This "partitions", or sub-divides, the table into separate units, one for each department.  In the problem you posted, it looks like you want to operate in the entire table, without sub-dividing it in any way.  To do that, just omit the PARTITION BY clause in the analytic ROW_NUMBER function, like this:
WITH got_r_num AS
    SELECT  deptno, ename, job, hiredate
    ,       ROW_NUMBER () OVER ( --  PARTITION BY  deptno
                                 ORDER BY      job
                                 ,             hiredate  DESC
                               )  AS r_num
    FROM    scott.emp
    WHERE   job  IN ('ANALYST', 'CLERK')
SELECT     deptno, ename, job, hiredate
FROM       got_r_num
WHERE      job     = 'ANALYST'
OR         r_num   = 1
ORDER BY   deptno