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SQL BETWEEN for text vs numeric values

BETWEEN is used in a WHERE clause to select a range of data between two values.
If I am correct whether the range’s endpoint are excluded or not is DBMS specific.
What I can not understand in the following:
If I have a table of values and I do the following query:

SELECT food_name 
    FROM health_foods 
    WHERE calories BETWEEN 33 AND 135;`  

The query returns as results rows including calories =33 and calories =135 (i.e. range endpoints are included).

But if I do:

SELECT food_name 
    FROM health_foods 
    WHERE food_name BETWEEN 'G' AND 'O';

I do not get rows with food_name starting with O. I.e. the end of the range is excluded.
For the query to work as expected I type:

SELECT food_name 
    FROM health_foods 
    WHERE food_name BETWEEN 'G' AND 'P';`   

My question is why is there such a difference for BETWEEN for numbers and text data?



Between is operating exactly the same way for numbers and for character strings. The two endpoints are included. This is part of the ANSI standard, so it is how all SQL dialects work.

The expression:

where num between 33 and 135

will match when num is 135. It will not match when number is 135.00001.

Similarly, the expression:

where food_name BETWEEN 'G' AND 'O'

will match ‘O’, but not any other string beginning with ‘O’.

Once simple kludge is to use “~”. This has the largest 7-bit ASCII value, so for English-language applications, it usually works well:

where food_name between 'G' and 'O~'

You can also do various other things. Here are two ideas:

where left(food_name, 1) between 'G' and 'O'
where food_name >= 'G' and food_name < 'P'

The important point, though, is that between works the same way regardless of data type.

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