Thread

1. The ignored "_" character

   PostgreSQL Bugs List <pgsql-bugs@postgresql.org> — 2001-05-07T07:01:28Z

   Laszlo Kohl (lkohl@matavnet.hu) reports a bug with a severity of 2
   The lower the number the more severe it is.
   
   Short Description
   The ignored "_" character
   
   Long Description
   Hi, 
   
   I am Laszlo from Hungary.
   I have some problem with PostgreSQL.
   
   Environment:
   PostgreSQL version: 7.0.3
   Server OS: RedHat 5.2 , Linux-Mandrake 7.2
   Client OS: RedHat 5.2 , Windows NT (pgAdmin) , Linux-Mandrake 7.2
   
   The problem:
   I create some users in database and then want to list them.
   The "_" character is ignored in query statement.
   The query: "select usename from pg_user where usename Like '%_u%' ;"
   produces the same result as the query: 
   "select usename from pg_user where usename Like '%u%' ;"
   
   
   
   Sample Code
   /* Create users... */
   create user i_adminuser  with sysid 40 password 'adminuser' createdb createuser ;
   create user i_login      with sysid 41 PASSWORD 'login';
   create user i_lekerdezo1 with sysid 45 password 'lekerdezo1';
   create user i_ugyintezo1 with sysid 46 password 'ugyintezo1' createuser ;
   
   /* The query 1: */
   select usename from pg_user where usename Like '%_u%' ;
   
   /* The Result: */
      usename
   --------------
    i_adminuser
    i_ugyintezo1
   (2 rows)
   
   /* The query 2: */
   select usename from pg_user where usename Like '%u%' ;
   
   /* The Result: */
      usename
   --------------
    i_adminuser
    i_ugyintezo1
   (2 rows)
   
   
   
   No file was uploaded with this report
   
   
   

2. Re: The ignored "_" character

   Karel Zak <zakkr@zf.jcu.cz> — 2001-05-07T08:12:53Z

   On Mon, May 07, 2001 at 03:01:28AM -0400, pgsql-bugs@postgresql.org wrote:
   > Laszlo Kohl (lkohl@matavnet.hu) reports a bug with a severity of 2
   > The lower the number the more severe it is.
   > 
   > Short Description
   > The ignored "_" character
   > 
   > Long Description
   > Hi, 
   > 
   > I am Laszlo from Hungary.
   > I have some problem with PostgreSQL.
   > 
   > Environment:
   > PostgreSQL version: 7.0.3
   > Server OS: RedHat 5.2 , Linux-Mandrake 7.2
   > Client OS: RedHat 5.2 , Windows NT (pgAdmin) , Linux-Mandrake 7.2
   > 
   > The problem:
   > I create some users in database and then want to list them.
   > The "_" character is ignored in query statement.
   > The query: "select usename from pg_user where usename Like '%_u%' ;"
   > produces the same result as the query: 
   > "select usename from pg_user where usename Like '%u%' ;"
   
    Sure it's not bug, please read something about the 'like' operator 
   first, en example:
   
   
   http://postgresql.wavefire.com/users-lounge/docs/7.1/user/functions-matching.html
   
   
   If pattern does not contain percent signs or underscore, then the pattern
   only represents the string itself; in that case LIKE acts like the equals
   operator. An underscore (_) in pattern stands for (matches) any single
   character; a percent sign (%) matches any string of zero or more
   characters.
   
    You must run:
   
    ... usename LIKE '%\\_u%' 
   
    Note two '\' must be used here because PostgreSQL parser first remove 
   and 'like' operator obtain second only.
   
   			Karel