Day of week problem

Question

Please take a look at the following sqlplus output:
SQL> select time, to_char(time, 'D') from rep.tttt where time >= trunc(sysdate, 'mm') group by time, to_char(time, 'D');
TIME T
01-JUN-05 4
02-JUN-05 5
03-JUN-05 6
04-JUN-05 7
05-JUN-05 1
06-JUN-05 2
07-JUN-05 3
08-JUN-05 4
09-JUN-05 5
10-JUN-05 6
11-JUN-05 7
TIME T
12-JUN-05 1
13-JUN-05 1
14-JUN-05 2
15-JUN-05 3
16-JUN-05 4
17-JUN-05 5
18-JUN-05 6
19-JUN-05 7
20-JUN-05 2
21-JUN-05 3
22-JUN-05 4
TIME T
23-JUN-05 5
24-JUN-05 6
25-JUN-05 7
26-JUN-05 1
26 rows selected.
SQL> select to_char(to_date('13.6.2005','dd.mm.rrrr'), 'D') from dual;
T
2
SQL> select to_char(to_date('12.6.2005','dd.mm.rrrr'), 'D') from dual;
T
1
SQL> select to_char(to_date('11.6.2005','dd.mm.rrrr'), 'D') from dual;
T
7
SQL> select parameter, value from nls_session_parameters;
PARAMETER VALUE
NLS_LANGUAGE AMERICAN
NLS_TERRITORY AMERICA
NLS_CURRENCY $
NLS_ISO_CURRENCY AMERICA
NLS_NUMERIC_CHARACTERS .,
NLS_CALENDAR GREGORIAN
NLS_DATE_FORMAT DD-MON-RR
NLS_DATE_LANGUAGE AMERICAN
NLS_SORT BINARY
NLS_TIME_FORMAT HH.MI.SSXFF AM
NLS_TIMESTAMP_FORMAT DD-MON-RR HH.MI.SSXFF AM
PARAMETER VALUE
NLS_TIME_TZ_FORMAT HH.MI.SSXFF AM TZR
NLS_TIMESTAMP_TZ_FORMAT DD-MON-RR HH.MI.SSXFF AM TZR
NLS_DUAL_CURRENCY $
NLS_COMP BINARY
NLS_LENGTH_SEMANTICS BYTE
NLS_NCHAR_CONV_EXCP FALSE
17 rows selected.
Can you please tell me why in the first SELECT phrase both '12-JUN-05' and '13-JUN-05' records have the same day number? Why '20-JUN-05' record doesn't have day number equal to 1?
Thaks!

Answer 1

perhaps some enteries are from 1995.