Requiring or Excluding FULLTEXT Search Words

4.14.1 Problem

You want to specifically require or disallow words in a FULLTEXT search.

4.14.2 Solution

Use a Boolean mode search.

4.14.3 Discussion

Normally, FULLTEXT searches return records that contain any of the words in the search string, even if some of them are missing. For example, the following query finds records that contain either of the names David or Goliath:

mysql> SELECT COUNT(*) FROM kjv
 -> WHERE MATCH(vtext) AGAINST('David Goliath');
+----------+
| COUNT(*) |
+----------+
| 934 |
+----------+

This behavior is undesirable if you want only records that contain both words. One way to do this is to rewrite the query to look for each word separately and join the conditions with AND:

mysql> SELECT COUNT(*) FROM kjv
 -> WHERE MATCH(vtext) AGAINST('David')
 -> AND MATCH(vtext) AGAINST('Goliath');
+----------+
| COUNT(*) |
+----------+
| 2 |
+----------+

As of MySQL 4.0.1, another way to require multiple words is with a Boolean mode search. To do this, precede each word in the search string with a + character and add IN BOOLEAN MODE after the string:

mysql> SELECT COUNT(*) FROM kjv
 -> WHERE MATCH(vtext) AGAINST('+David +Goliath' IN BOOLEAN MODE)
+----------+
| COUNT(*) |
+----------+
| 2 |
+----------+

Boolean mode searches also allow you to exclude words. Just precede any disallowed word with a - character. The following queries select kjv records containing the name David but not Goliath, or vice versa:

mysql> SELECT COUNT(*) FROM kjv
 -> WHERE MATCH(vtext) AGAINST('+David -Goliath' IN BOOLEAN MODE)
+----------+
| COUNT(*) |
+----------+
| 928 |
+----------+
mysql> SELECT COUNT(*) FROM kjv
 -> WHERE MATCH(vtext) AGAINST('-David +Goliath' IN BOOLEAN MODE)
+----------+
| COUNT(*) |
+----------+
| 4 |
+----------+

Another useful special character in Boolean searches is *; when appended to a search word, it acts as a wildcard operator. The following query finds records containing not only whirl, but also words such as whirls, whirleth, and whirlwind:

mysql> SELECT COUNT(*) FROM kjv
 -> WHERE MATCH(vtext) AGAINST('whirl*' IN BOOLEAN MODE);
+----------+
| COUNT(*) |
+----------+
| 28 |
+----------+