where clause

  • From: "David Boyd" <davidb158@xxxxxxxxxxx>
  • To: oracle-l@xxxxxxxxxxxxx
  • Date: Fri, 06 Feb 2004 14:55:21 -0500

Hi List,

I found following results that I don't understand.

SQL> desc test
Name                                      Null?    Type
----------------------------------------- -------- -----------------
STATUS_FLAG                                        CHAR(1)

SQL> SELECT COUNT(*) FROM test;

  COUNT(*)
----------
      1681

SQL> SELECT COUNT(*) FROM test WHERE status_flag IS NULL;

  COUNT(*)
----------
      1638

SQL> SELECT COUNT(*) FROM test WHERE status_flag ='A';

  COUNT(*)
----------
         5

SQL> SELECT COUNT(*) FROM test WHERE status_flag ='S';

  COUNT(*)
----------
        38

SQL> SELECT COUNT(*) FROM test WHERE status_flag !='A';

  COUNT(*)
----------
        38

I thought the last query should return 1676 (status_flag ='S' + status_flag
is null) instead of 38 (status_flag ='S' only).  Any ideas???

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