###STRUCTURE
T9 class is responsible for a T9 cipher code and search.
DB class is responsible for all database operations.
index.php has a user interface, imitation of a keyboard.
MYSQL.sql is a file with the dump of database.
###TEST DATA
The project has a small database, only 5 records. For tests, please use the input data from the technical test, i.e.: for 688 fits to OTTo and NUTzer, the 724 for SCHmidt and RAHmen.
Input data is restricted to 4 symbols only. There will be no alarm message, just a restriction.
###MYSQL
Since the requirement for the database was, that we'll have more than 1 mln. records, I used MyISAM engine for the phone_book table instead of InnoDB (ignoring better data recovery opportunity, available in InnoDB in this case) for the following reasons:
- it works faster on select operations;
- MyISAM has fulltext index that allowed to use here MATCH AGAINST search, which is much faster than "LIKE" and fits for our case the best.
I used index for 2 fields to have opportunity to perform the search both on the name and last_name fields.