How to generate report with dynamic variable number of columns?

Question

How to generate report with dynamic variable number of columns?
I need to generate a report with varying column names (state names) as follows:
SELECT AK, AL, AR,... FROM States ;
I get these column names from the result of another query.
In order to clarify my question, Please consider following table:
CREATE TABLE TIME_PERIODS (
PERIOD     VARCHAR2 (50) PRIMARY KEY
CREATE TABLE STATE_INCOME (
     NAME     VARCHAR2 (2),
     PERIOD     VARCHAR2 (50)     REFERENCES TIME_PERIODS (PERIOD) ,
     INCOME     NUMBER (12, 2)
I like to generate a report as follows:
AK CA DE FL ...
PERIOD1 1222.23 2423.20 232.33 345.21
PERIOD2
PERIOD3
Total 433242.23 56744.34 8872.21 2324.23 ...
The TIME_PERIODS.Period and State.Name could change dynamically.
So I can't specify the state name in Select query like
SELECT AK, AL, AR,... FROM
What is the best way to generate this report?

Answer 1

SQL> -- test tables and test data:
SQL> CREATE TABLE states
  2    (state VARCHAR2 (2))
  3  /
Table created.
SQL> INSERT INTO states
  2  VALUES ('AK')
  3  /
1 row created.
SQL> INSERT INTO states
  2  VALUES ('AL')
  3  /
1 row created.
SQL> INSERT INTO states
  2  VALUES ('AR')
  3  /
1 row created.
SQL> INSERT INTO states
  2  VALUES ('CA')
  3  /
1 row created.
SQL> INSERT INTO states
  2  VALUES ('DE')
  3  /
1 row created.
SQL> INSERT INTO states
  2  VALUES ('FL')
  3  /
1 row created.
SQL> CREATE TABLE TIME_PERIODS
  2    (PERIOD VARCHAR2 (50) PRIMARY KEY)
  3  /
Table created.
SQL> INSERT INTO time_periods
  2  VALUES ('PERIOD1')
  3  /
1 row created.
SQL> INSERT INTO time_periods
  2  VALUES ('PERIOD2')
  3  /
1 row created.
SQL> INSERT INTO time_periods
  2  VALUES ('PERIOD3')
  3  /
1 row created.
SQL> INSERT INTO time_periods
  2  VALUES ('PERIOD4')
  3  /
1 row created.
SQL> CREATE TABLE STATE_INCOME
  2    (NAME   VARCHAR2 (2),
  3       PERIOD VARCHAR2 (50) REFERENCES TIME_PERIODS (PERIOD),
  4       INCOME NUMBER (12, 2))
  5  /
Table created.
SQL> INSERT INTO state_income
  2  VALUES ('AK', 'PERIOD1', 1222.23)
  3  /
1 row created.
SQL> INSERT INTO state_income
  2  VALUES ('CA', 'PERIOD1', 2423.20)
  3  /
1 row created.
SQL> INSERT INTO state_income
  2  VALUES ('DE', 'PERIOD1', 232.33)
  3  /
1 row created.
SQL> INSERT INTO state_income
  2  VALUES ('FL', 'PERIOD1', 345.21)
  3  /
1 row created.
SQL> -- the basic query:
SQL> SELECT   SUBSTR (time_periods.period, 1, 10) period,
  2             SUM (DECODE (name, 'AK', income)) "AK",
  3             SUM (DECODE (name, 'CA', income)) "CA",
  4             SUM (DECODE (name, 'DE', income)) "DE",
  5             SUM (DECODE (name, 'FL', income)) "FL"
  6  FROM     state_income, time_periods
  7  WHERE    time_periods.period = state_income.period (+)
  8  AND      time_periods.period IN ('PERIOD1','PERIOD2','PERIOD3')
  9  GROUP BY ROLLUP (time_periods.period)
10  /
PERIOD             AK         CA         DE         FL                                             
PERIOD1       1222.23     2423.2     232.33     345.21                                             
PERIOD2                                                                                            
PERIOD3                                                                                            
              1222.23     2423.2     232.33     345.21                                             
SQL> -- package that dynamically executes the query
SQL> -- given variable numbers and values
SQL> -- of states and periods:
SQL> CREATE OR REPLACE PACKAGE package_name
  2  AS
  3    TYPE cursor_type IS REF CURSOR;
  4    PROCEDURE procedure_name
  5        (p_periods   IN     VARCHAR2,
  6         p_states    IN     VARCHAR2,
  7         cursor_name IN OUT cursor_type);
  8  END package_name;
  9  /
Package created.
SQL> CREATE OR REPLACE PACKAGE BODY package_name
  2  AS
  3    PROCEDURE procedure_name
  4        (p_periods   IN     VARCHAR2,
  5         p_states    IN     VARCHAR2,
  6         cursor_name IN OUT cursor_type)
  7    IS
  8        v_periods          VARCHAR2 (1000);
  9        v_sql               VARCHAR2 (4000);
10        v_states          VARCHAR2 (1000) := p_states;
11    BEGIN
12        v_periods := REPLACE (p_periods, ',', ''',''');
13        v_sql := 'SELECT SUBSTR(time_periods.period,1,10) period';
14        WHILE LENGTH (v_states) > 1
15        LOOP
16          v_sql := v_sql
17          || ',SUM(DECODE(name,'''
18          || SUBSTR (v_states,1,2) || ''',income)) "' || SUBSTR (v_states,1,2)
19          || '"';
20          v_states := LTRIM (SUBSTR (v_states, 3), ',');
21        END LOOP;
22        v_sql := v_sql
23        || 'FROM     state_income, time_periods
24            WHERE    time_periods.period = state_income.period (+)
25            AND      time_periods.period IN (''' || v_periods || ''')
26            GROUP BY ROLLUP (time_periods.period)';
27        OPEN cursor_name FOR v_sql;
28    END procedure_name;
29  END package_name;
30  /
Package body created.
SQL> -- sample executions from SQL:
SQL> VARIABLE g_ref REFCURSOR
SQL> EXEC package_name.procedure_name ('PERIOD1,PERIOD2,PERIOD3','AK,CA,DE,FL', :g_ref)
PL/SQL procedure successfully completed.
SQL> PRINT g_ref
PERIOD             AK         CA         DE         FL                                             
PERIOD1       1222.23     2423.2     232.33     345.21                                             
PERIOD2                                                                                            
PERIOD3                                                                                            
              1222.23     2423.2     232.33     345.21                                             
SQL> EXEC package_name.procedure_name ('PERIOD1,PERIOD2','AK,AL,AR', :g_ref)
PL/SQL procedure successfully completed.
SQL> PRINT g_ref
PERIOD             AK         AL         AR                                                        
PERIOD1       1222.23                                                                              
PERIOD2                                                                                            
              1222.23                                                                              
SQL> -- sample execution from PL/SQL block
SQL> -- using parameters derived from processing
SQL> -- cursors containing results of other queries:
SQL> DECLARE
  2    CURSOR c_period
  3    IS
  4    SELECT period
  5    FROM   time_periods;
  6    v_periods   VARCHAR2 (1000);
  7    v_delimiter VARCHAR2 (1) := NULL;
  8    CURSOR c_states
  9    IS
10    SELECT state
11    FROM   states;
12    v_states    VARCHAR2 (1000);
13  BEGIN
14    FOR r_period IN c_period
15    LOOP
16        v_periods := v_periods || v_delimiter || r_period.period;
17        v_delimiter := ',';
18    END LOOP;
19    v_delimiter := NULL;
20    FOR r_states IN c_states
21    LOOP
22        v_states := v_states || v_delimiter || r_states.state;
23        v_delimiter := ',';
24    END LOOP;
25    package_name.procedure_name (v_periods, v_states, :g_ref);
26  END;
27  /
PL/SQL procedure successfully completed.
SQL> PRINT g_ref
PERIOD             AK         AL         AR         CA         DE         FL                       
PERIOD1       1222.23                           2423.2     232.33     345.21                       
PERIOD2                                                                                            
PERIOD3                                                                                            
PERIOD4                                                                                            
              1222.23                           2423.2     232.33     345.21