Re: no records returned
От | James Moe |
---|---|
Тема | Re: no records returned |
Дата | |
Msg-id | auto-000000760067@sohnen-moe.com обсуждение исходный текст |
Ответ на | Re: no records returned (Lynn.Tilby@asu.edu) |
Список | pgsql-general |
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On Sat, 25 Oct 2003 20:19:49 -0700 (MST), Lynn.Tilby@asu.edu wrote: >Could you explain to a newbie WHY the like and % at >the end of the literal works when the normal select does >not? > The "%" is a wildcard character in SQL, the same as "*" in many file systems. It matches 0 or more characters. Also "_" matches any single character, similar to "?", or "." in regular expressions. There is likely one or more spaces after the visible characters. Using a "%" after ZRAN matches ZRAN plus anything else following that pattern. The implementation of the LIKE operator is a somewhat uneven in my experience. Depending on the database it can only be used to match strings, or to do a case-insensitive compare, or is equivalent to "=" with "=" extended to string operations. In most cases, though, the best practice is to use it for strings especially when using regular expressions like "%"; and to use "=" for numeric and exact matching. - -- jimoe at sohnen-moe dot com pgp/gpg public key: http://www.keyserver.net/en/ -----BEGIN PGP SIGNATURE----- Version: PGPfreeware 5.0 OS/2 for non-commercial use Comment: PGP 5.0 for OS/2 Charset: cp850 wj8DBQE/nE7isxxMki0foKoRAkJjAJ9lpqeC8y+Go0tXclwIM8XzvaRd1QCgtn8i 26WzEwf8HNPY5iqY6ZckrmY= =DY5x -----END PGP SIGNATURE-----
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