Switch row into a column in the view

Question

EMP TABLE
empid pay_type_id      pay_factor
101      A           10
111      A           15
112      B           3000
101      C           250
111      C           250
PAY_TYPES table
pay_type_id      pay_type_code description
A           var           variable pay
B           com           commission
C           car           car allowance
D           bon           bonus
View I would like to create should display like below. there cab be many pay-type-codes and these should not be hardcoded!
empid      var      com      car      bon
101      10      null      250      null
111      15      null      250      null
112      null      3000 null      null
basically I want to switch 'pay_type_id's as a column in the view

Answer 1

Hi,
Use Dynamic SQL.
For example:
How to Pivot a Table with a Dynamic Number of Columns
This works in any version of Oracle
The "SELECT ... PIVOT" feature introduced in Oracle 11
is much better for producing XML output.
Say you want to make a cross-tab output of
the scott.emp table.
Each row will represent a department.
There will be a separate column for each job.
Each cell will contain the number of employees in
     a specific department having a specific job.
The exact same solution must work with any number
of departments and columns.
(Within reason: there's no guarantee this will work if you
want 2000 columns.)
Case 0 "Basic Pivot" shows how you might hard-code three
job types, which is exactly what you DON'T want to do.
Case 1 "Dynamic Pivot" shows how get the right results
dynamically, using SQL*Plus. 
(This can be easily adapted to PL/SQL or other tools.)
NOTE: Using SQL*Plus file I/O, as in this example, is just
one of many ways to do dynamic SQL.
PROMPT     ==========  0. Basic Pivot  ==========
SELECT     deptno
,     COUNT (CASE WHEN job = 'ANALYST' THEN 1 END)     AS analyst_cnt
,     COUNT (CASE WHEN job = 'CLERK'   THEN 1 END)     AS clerk_cnt
,     COUNT (CASE WHEN job = 'MANAGER' THEN 1 END)     AS manager_cnt
FROM     scott.emp
WHERE     job     IN ('ANALYST', 'CLERK', 'MANAGER')
GROUP BY     deptno
ORDER BY     deptno
PROMPT     ==========  1. Dynamic Pivot  ==========
--     *****  Start of dynamic_pivot.sql  *****
-- Suppress SQL*Plus features that interfere with raw output
SET     FEEDBACK     OFF
SET     PAGESIZE     0
SPOOL     p:\sql\cookbook\dynamic_pivot_subscript.sql
SELECT     DISTINCT
     ',     COUNT (CASE WHEN job = '''
||     job
||     ''' '     AS txt1
,     'THEN 1 END)     AS '
||     job
||     '_CNT'     AS txt2
FROM     scott.emp
ORDER BY     txt1;
SPOOL     OFF
-- Restore SQL*Plus features suppressed earlier
SET     FEEDBACK     ON
SET     PAGESIZE     50
SPOOL     p:\sql\cookbook\dynamic_pivot.lst
SELECT     deptno
@@dynamic_pivot_subscript
FROM     scott.emp
GROUP BY     deptno
ORDER BY     deptno
SPOOL     OFF
--     *****  End of dynamic_pivot.sql  *****
EXPLANATION:
The basic pivot assumes you know the number of distinct jobs,
and the name of each one.  If you do, then writing a pivot query
is simply a matter of writing the correct number of ", COUNT ... AS ..."\
lines, with the name entered in two places on each one.  That is easily
done by a preliminary query, which uses SPOOL to write a sub-script
(called dynamic_pivot_subscript.sql in this example).
The main script invokes this sub-script at the proper point.
In practice, .SQL scripts usually contain one or more complete
statements, but there's nothing that says they have to.
This one contains just a fragment from the middle of a SELECT statement.
Before creating the sub-script, turn off SQL*Plus features that are
designed to help humans read the output (such as headings and
feedback messages like "7 rows selected.", since we do not want these
to appear in the sub-script.
Turn these features on again before running the main query.
*/By pure chance, I still had this script in my paste buffer from ansering [another thread|http://forums.oracle.com/forums/thread.jspa?threadID=1013260&tstart=0].