How to populate a 'map' table from words of a text?

Question

Having the database structure that follows:

CREATE TABLE articles
(
article_id int(11) unsigned NOT NULL AUTO_INCREMENT,
article text,
PRIMARY KEY(article_id)
) ENGINE=InnoDB;

CREATE TABLE words
(
word_id int(11) unsigned NOT NULL AUTO_INCREMENT,
word varchar(255),
PRIMARY KEY(word_id)
) ENGINE=InnoDB;

CREATE TABLE word_map
(
article_id int(11) unsigned NOT NULL,
word_id int(11) unsigned NOT NULL,
FOREIGN KEY(article_id) REFERENCES articles(article_id) ON DELETE CASCADE,
FOREIGN KEY(word_id) REFERENCES words(word_id) ON DELETE CASCADE,
PRIMARY KEY(article_id, word_id)
) ENGINE=InnoDB;

How can I split the text column in the article table to find the words which exist in the words table and, then, INSERT the words into word_map?

Now I am doing this in PHP by splitting the text into words, then, finding word_id for each word, and then, INSERT INTO word_map (article_id, word_id).