What is this code doing?
DBAsupport.com Forums - Powered by vBulletin
Results 1 to 2 of 2

Thread: What is this code doing?

  1. #1
    Join Date
    Nov 2001
    Location
    New Brunswick, NJ
    Posts
    67
    I'm looking at somebody elses code, and I'm tring to figure out what is going on?

    What does the select 1 etc.
    unioned with Select 2,1 etc doing?

    Help!

    Thanks,

    Paul

    select 1 order_by1, column_id order_by2,
    decode(column_id, 1, 'select ', ' ||') ||
    '''"''' || '||' || decode(data_type,
    'NUMBER', 'to_char(',
    'DATE', 'to_char(') || column_name ||
    decode(data_type,
    'NUMBER', ')',
    'DATE', ',''DD-MON-YYYY'')')
    || ' || ' || '''",''' text
    from all_tab_columns
    where table_name = Upper('&tablename')
    and data_type != 'LONG'
    and owner = Upper('&Owner')
    UNION
    select 2, 1, ' from &tablename'
    from dual
    UNION
    select 3, 1, '&whereclause'
    from dual
    order by 1,2;

  2. #2
    Join Date
    Apr 2001
    Posts
    118
    They're just using a "trick" to make sure that the rows returned from the first query in the statement come before the ones from the second query and before the rows from the third query. It is perfectly valid to specify a literal value in a select statement. BY "tagging" each row from each query with a numeric value, the ORDER BY at the end will ensure that the rows from the first query come first, the rows from the second one next and, finally, the rows from the third.

    HTH,

    Heath

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  


Click Here to Expand Forum to Full Width