ZEND PHP 5 Certification STUDY GUIDE

Database Programming ” 147
CREATE INDEX
ON ([, ..., ]);
For example, suppose we wanted to create a unique index on the isbn column of the
book table we created earlier:
CREATE INDEX book_isbn ON book (isbn);
i
The name of the index is, of course, entirely arbitrary and only has a meaning when
deleting the latter; however, it must still be unique and abide by the naming rules we
described above.
Foreign-key relationships are created either when a table is created, or at a later
date with an altering statement. For example, suppose we wanted to add a table that
contains a list of all of the chapter titles for every book:
CREATE TABLE book_chapter (
isbn VARCHAR(13) REFERENCES book (id),
chapter_number INT NOT NULL,
chapter_title VARCHAR(255)
);
This code creates a one-to-many relationship between the parent table book and the
child table book_chapter based on the isbn field. Once this table is created, you can
only add a row to it if the ISBN you specify exists in book.
To create a one-to-one relationship, you can simply make the connective columns of
a one-to-many relationship the primary key of the child table
Licensed to 482634 - Amber Barrow (itsadmin@deakin.edu.au)
Dropping Objects
The act of deleting an object from a schema—be it a table, an index, or even the
schema itself—is called dropping. It is performed by a variant of the DROP statement:
DROP TABLE book_chapter;