RE: Selecte nd NULLs

NULL is unknown, so you won't get results back on equality comparisons (= or <>).

http://docs.oracle.com/cd/B19306_01/server.102/b14200/sql_elements005.htm

Thanks,
T. J.

From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of James Clarence Allen (CENSUS/EPD FED) Sent: Wednesday, March 25, 2015 9:04 AM
To: Oracle Chat freelist
Subject: Selecte nd NULLs

Someone,

I am doing a simple select.

SQL>select distinct dbname from mytable where cluster != 'orrac1';

I have a three column table "mytable" (dbname,sid,cluster). The table contains 206 total rows/136 rows with distinct dbname. No indices are on the table.

Some dbnames are not in a cluster (single server) so the cluster column is null.

When I run the select above the rows with the null in cluster column are not returned.

Shouldn't all rows be turned except what I am filtering out?

Sincerely,

Jim Allen
Database Support Lead, MASSDB Staff

Schedule: Mon-Fri, 7:00am-3:30pm
Tel: 1-301-763-7501

Cell: 1-202-604-7286
Database Help Desk: X34944
Support Email: James.Clarence.Allen_at_census.gov<mailto:James.Clarence.Allen_at_census.gov> Internal Website: http://epd.econ.census.gov/offices/massdb/

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