Posts tagged regular expressions

Say you have a list of movie titles, and you want to either sort them, or search through them, and some of them have “The ” at the start, for example:

• The Simpsons
• Simpson Street

When doing a MySQL search:

SELECT * FROM movies WHERE title LIKE "The Simp%";

Would only return the first row. But if you are working in a company where there is no standard set, the movie title could be formatted as “Simpsons, The” – and then, it won’t be found.

To solve this, you could replace the “The ” letters with blank, and then sort out the field contents during the query:

$str_query = preg_replace("/(title like \"(the )(.*)\%\")/i",
    "REPLACE(LOWER(title), \"the \", \"\") LIKE (\"$3%\")",
    $str_query);

This will change :

"(title LIKE "The Simpsons")"

to,

"(title LIKE "Simpsons")"

But, the (the) in line 2 tells PHP to only replace it if starts with “The ” (case insenstive).

However, what if you want to search for “the”  (not sure why you would…)

You need to do a negative lookahead, to tell the expression to only carry on, if the search phrase is not exactly “the”

if (preg_match("/(title like \"(?!the)(.*)\%\")/i", $str_query)) {

The (?!the) is the readahead.

(.*) matches any string but it is greedy and you have to be carfeul that it doesn’t just accept everything to the end of $str_query. (but its okay in our case, as we are looking for \% (the LIKE wildcard))

After all this, we can run:

SELECT * FROM movies WHERE $str_query;

But what about sorting? All the titles beginning with “The” will appear in the T section. Whereas really, we want the Simpsons to appear in the S section.

Add an easy ORDER BY clause here:

SELECT * FROM movies WHERE $str_query ORDER BY (REPLACE(title, "the ", "") ASC;

Sorted!