Re: Join Table

From the performance point of view, should I use cursor instead of joining table to select data?

Roland Svensson (roland.svensson_at_localhost.se) wrote:
: On 28 Sep 1998 08:22:44 GMT, paulkcng_at_news.netvigator.com (Ng K C
: Paul) wrote:
:
: >No, for your join in your select statement, only one row would be returned.
: >What I want is the join that returns 5 rows as using the key from tab1
: >and tab2 but the keys are different value. I want to know if it
: >is possible to join tables with different key values as indicated in my
: >sample data.
: >: >
: >: >tab1_key tab2_key
: >: >-------- --------
: >: >10 9
: >: >20 18
: >: >30 27
: >: >40 39
: >: >50 50
: >: >
: Maybe this is what you want:
: select tab1_key, tab2_key from
: (select r1.tab1_key mx, max(r3.tab1_key) mi
: from tab1 r1, tab1 r3
: where r3.tab1_key < r1.tab1_key
: group by r1.tab1_key
: UNION select min(tab1_key), 0 from tab1 ) t1,
: tab1, tab2
: where t1.mi < tab2_key and t1.mx >= tab2_key
: and t1.mx = tab1_key;
: This will join tab2 to tab1 such as tab2_keys will join to
: the tab1_key that is the smallest one greater or equal to
: tab2_key. I guess the performance will be horrible.
:
:
:
: --
: Regards,
: Roland
Received on Tue Sep 29 1998 - 00:00:00 CDT