Version: PostgreSQL 7.1.2 on sparc-sun-solaris2.5.1, compiled by GCC 2.95 Hi, when using SELECT queries chained by INTERSECT i get confused about the behavour of the INTERSECT operation. I try to outline this with the following examples.
Example (Field query_desc is of type TEXT): select query_desc FROM blasthits_obj_3_q3_db3; Returning: 4114 rows select distinct query_desc FROM blasthits_obj_3_q3_db3 ; Returning: 333 rows Now intersecting this table with itself: select query_desc FROM blasthits_obj_3_q3_db3 INTERSECT select query_desc FROM blasthits_obj_3_q3_db3; Returning: 333 rows thats ok till now Adding a second INTERSECT: select query_desc FROM blasthits_obj_3_q3_db3 INTERSECT select query_desc FROM blasthits_obj_3_q3_db3 INTERSECT select query_desc FROM blasthits_obj_3_q3_db3; Returning: 157 rows hmm.. ok lets try it with brackets: select query_desc FROM blasthits_obj_3_q3_db3 INTERSECT (select query_desc FROM blasthits_obj_3_q3_db3 INTERSECT select query_desc FROM blasthits_obj_3_q3_db3); Returning: 333 rows ok...and now with a third INTERSECT select query_desc FROM blasthits_obj_3_q3_db3 INTERSECT ((select query_desc FROM blasthits_obj_3_q3_db3 INTERSECT select query_desc FROM blasthits_obj_3_q3_db3) INTERSECT SELECT query_desc FROM blasthits_obj_3_q3_db3); Returning: 157 rows. WHY ? I tried to reproduce this on a small table containing one column and 7 integer entries (2 duplicates). But in this case it works as expected, even without brackets. So mybe there is a problem with the data type TEXT and INTERSECT ? Any idea ? ------------------------------------------------------------------------------- Dipl.-Inform. Michael Beckstette Office: M3-129 AG-PI / Technische Fakultaet EMail:[EMAIL PROTECTED] Universitaet Bielefeld Fon: +49-521-106-2914 Postfach 100131 Fax: +49-521-106-6411 D-33501 BIELEFELD Germany ---------------------------(end of broadcast)--------------------------- TIP 3: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly
