HAVING is analogous to WHERE, but it applies to group characteristics rather than to single records.
mysql>
mysql>
mysql> CREATE TABLE mytable
-> (
-> rec_id INT UNSIGNED NOT NULL AUTO_INCREMENT,
-> name VARCHAR(20) NOT NULL,
-> trav_date DATE NOT NULL,
-> miles INT NOT NULL,
-> PRIMARY KEY (rec_id)
-> );
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql> INSERT INTO mytable (name,trav_date,miles)
-> VALUES
-> ('Ben','2010-11-30',152),
-> ('Suzi','2010-11-29',391),
-> ('Henry','2010-11-29',300),
-> ('Henry','2010-11-27',96),
-> ('Ben','2010-11-29',131),
-> ('Henry','2010-11-26',115),
-> ('Suzi','2010-12-02',502),
-> ('Henry','2010-12-01',197),
-> ('Ben','2010-12-02',79),
-> ('Henry','2010-11-30',203)
-> ;
Query OK, 10 rows affected (0.00 sec)
Records: 10 Duplicates: 0 Warnings: 0
mysql>
mysql> SELECT COUNT(*), name
-> FROM mytable
-> GROUP BY name
-> HAVING COUNT(*) > 3;
+----------+-------+
| COUNT(*) | name |
+----------+-------+
| 5 | Henry |
+----------+-------+
1 row in set (0.00 sec)
mysql>
mysql> drop table mytable;
Query OK, 0 rows affected (0.00 sec)