On Mon, Dec 26, 2005 at 03:47:36PM +0000, kenichi nakanishi wrote: > I found something strange result when using a following sql sentence, > "select xxx || ' / ' || yyyy || ' / ' || zzzz as aaa from TABLE", > sometime I could get empty results. > When using same scentence on linux platform, I could get correct results. > So I think it's a bug on windows version.
Do the Linux and Windows platforms have the same data? Might any of the columns on the Windows system be NULL? Concatenating anything with NULL results in NULL, so that could be the problem. test=> CREATE TABLE foo (col1 text, col2 text); CREATE TABLE test=> INSERT INTO foo (col1, col2) VALUES ('aaa', 'bbb'); INSERT 0 1 test=> INSERT INTO foo (col1, col2) VALUES ('ccc', NULL); INSERT 0 1 test=> INSERT INTO foo (col1, col2) VALUES (NULL, 'ddd'); INSERT 0 1 test=> SELECT col1, col2, col1 || col2 FROM foo; col1 | col2 | ?column? ------+------+---------- aaa | bbb | aaabbb ccc | | | ddd | (3 rows) If you want to treat NULL as an empty string then use COALESCE: test=> SELECT col1, col2, COALESCE(col1, '') || COALESCE(col2, '') FROM foo; col1 | col2 | ?column? ------+------+---------- aaa | bbb | aaabbb ccc | | ccc | ddd | ddd (3 rows) -- Michael Fuhr ---------------------------(end of broadcast)--------------------------- TIP 3: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faq