Question

I am not able to make this out: Between eliminates use of >= and <=

…but when i tried this query:

SELECT *  
  FROM names 
 WHERE name >= 'Ankit' 
   AND name <= 'P'

…it gives output:

name
------
Ankit
Mac
Bob

When I tried:

SELECT *  
  FROM names  
 WHERE name BETWEEN 'Ankit' AND 'P'

…it gives output:

name
------
Ankit

Can you explain this why?

Answer 1

First, Oracle VARCHAR2 type is case sensitive.

Second, check that you do not have spaces in the beginning of name like this:

" Bob"
" Mac"

Use trim function to check if this causes the problem:

SELECT *  
FROM names  
WHERE trim(name) BETWEEN 'Ankit' AND 'P'

If this does not help, check that language and sort order are correct for your database.

Edit:
Since above advice did not solve your problem, you could try following:

1. Maybe you have some other non-printable characters in field. Use Oracle DUMP function to check:

   SELECT DUMP(name), name FROM names
   

   You should get something like this:

   Typ=1 Len=3: 66,111,98   Bob
   ...
   

   Verify that Len is correct length.

2. Check NLS parameters so that they are not inadvertently changed to something that does not work for your database:

   SELECT * FROM NLS_SESSION_PARAMETERS
   SELECT * FROM NLS_DATABASE_PARAMETERS
   SELECT * FROM NLS_INSTANCE_PARAMETERS
   

   Check results of these three queries and verify that parameters on sort, language and character set are correct.