Question

I’m trying to query a database of Book titles based on the first letter of the title. However, I want to ignore common words such as “The” and “A”.

So when searching for books that start with the letter “T”

"The Adventures of Huck Finn" - would NOT be matched
"Transformation of a Runner" - would be matched

I’m not very experienced with REGEX, but this is what I have so far (where $first_letter could equal ‘t’)

... WHERE title = '^[(a )(the )]*[$first_letter]' ...

This successfully matches book titles that start with a particular letter even after the words “A” or “The”, but doesn’t ignore those words. So if $first_letter=’t’, it would match BOTH books mentioned above.

I’ve tried googling it, but haven’t found any solutions. Any help would be greatly appreciated.

Thanks in advance.

Kevin

Answer 1

The regular expression you’ve written isn’t valid. []s are used to denote what is called a character class. Everything you enter between the brackets (with some characters potentially needing to be escaped, such as the literal characters [ and ]) is treated as standing-in for a single character.

edit After re-reading my answer, I realized lookaround wasn’t a good way to approach this.

The functionality you’re groping for is called negative lookahead, negative lookbehind, or some similar variant. I’m unsure whether MySQL’s regex flavor supports it, but I don’t think it would be a good fit for this problem.

Alternatively, you could do a regex that looks like this:

^((a|the|of|and) )?[letter of interest]

The breakdown:

• There are two groups
• • The inner-most group looks for instances of words you want to ignore
• • The outer-most group just adds a space to the end of that
• The ? asserts that there could be 0 or 1 instances of this group

You’ll have to do the legwork of translating this into MySQL regex syntax yourself. My apologies.