Efficiently search for a prefix range in SQL Server

Question

Let's say I want all records with a prefix between two user-supplied alphanumeric values of the same length. Thus, if the user enters A010 and A025, I want to return A0101, A0200 and A0259.

What I've tried:

1. Obviously, I cannot use WHERE myText BETWEEN @from and @to, because that won't return A0259.

2. Technically, WHERE LEFT(myText, @len) BETWEEN @from AND @to, would be exactly what I want, but that kills SARGability.

3. I could use WHERE myText BETWEEN @from and @to + 'zzzzzzzzzzz', but that is an ugly hack and potentially error-prone. (Is z really the highest character? Did I use enough "padding" characters?)

4. I could "explode" the range and search for every possible prefix, e.g. WHERE (myText LIKE 'A01%' OR myText LIKE 'A020%' OR myText LIKE 'A021%' ...), but that's a lot of work.

Is there some smart solution that I've missed? I'll probably use option 3 to solve the problem (since I know about the length and the range of allowed characters), but I'm curious about the general case.

Answer 1

If you use the >= and < operators you can return the required range by "increasing the second argument" by 1. Technically, replacing the last character ('5') with the next character ('6') in the character set.

Below is a query that returns all the rows in your range of A010 and A025. To get this I pass 'A026' as the second argument. The expression < 'A026' includes the value 'A0259456546'.

DECLARE @Test TABLE
(
    Val NVARCHAR(100)
) ;

INSERT @Test
VALUES ('A0004534543'), 
       ('A01034950834'), 
       ('A020043553'), 
       ('A0259456546'), 
       ('A0264565464') ;

SELECT  *

FROM    @Test

WHERE   Val >= 'A010' 
        AND Val < 'A026' ;