How to use quarter format in "to_date()" function?

Question

Hi,
I'm trying to use to_date() function with quarter format. How do I specify the format?
For example to convert '2002 quarter 1' using the to_date function.
I tried to_date('20021', 'YYYYQ'), and I got ORA-01820 cannot appear in date input format.
Please help, thank you!!!

Answer 1

You cannot use Q when inputting data, only when retrieving data. When inputting, you must enter a valid date. Oracle has to store a date and if you just enter a quarter, it can't figure out what date to store. See the examples below:
SQL> -- test table:
SQL> CREATE TABLE test_table
  2    (test_date DATE)
  3  /
Table created.
SQL> -- the wrong way to input:
SQL> INSERT INTO test_table (test_date)
  2  VALUES (TO_DATE ('2002-1', 'YYYY-Q'))
  3  /
VALUES (TO_DATE ('2002-1', 'YYYY-Q'))
ERROR at line 2:
ORA-01820: format code cannot appear in date input format
SQL> -- the right way to input:
SQL> INSERT INTO test_table (test_date)
  2  VALUES (TO_DATE ('27-OCT-2002', 'DD-MON-YYYY'))
  3  /
1 row created.
SQL> -- to output:
SQL> COLUMN "Year and Quarter" FORMAT A16
SQL> SELECT test_date,
  2         TO_CHAR (test_date, 'YYYY-Q') AS "Year and Quarter"
  3  FROM   test_table
  4  /
TEST_DATE   Year and Quarter
27-OCT-2002 2002-4
1 row selected.