Programming PHP

• Applications that want to use the Save As option for Excel data should issue a
CREATE TABLE statement for the new table and then do subsequent INSERT operations
into the new table. INSERT statements result in an append to the table. No
other operations can be done on the table until it is closed and reopened the first
time. After the table is closed the first time, no subsequent inserts can be done.
• The Excel ODBC driver does not support DELETE, UPDATE, CREATE INDEX, DROP
INDEX, orALTER TABLE statements. While it is possible to update values, DELETE
statements do not remove a row from a table based on an Excel spreadsheet.
If you can work with these limitations, combining PHP with Excel through an ODBC
interface may be acceptable.
Although the primary source of documentation for the Excel ODBC drivers is the
Microsoft Desktop Database Drivers Help file, invoked from the Help buttons under
ODBC Administrator, you can also determine some of the peculiarities of Excel’s
support for ODBC via Excel’s online help. However, it will take a good deal of poking
around to find what you need. Much of the time, you will find yourself searching
for answers through your favorite search engine, or in the annotated help files at
http://www.php.net.
Working with Access
A more sophisticated example of PHP’s ODBC support is demonstrated in our next
example. Here we store the phone-list data in an Access database, which has slightly
more robust ODBC support.
We use only four ODBC functions from PHP:
$handle = odbc_connect(dsn, user, password [, cursor_type]);
$success = odbc_autocommit(handle, status);
$result = odbc_exec(handle, sql);
$cols = odbc_fetch_into(result [, rownumber, result_array]);
There are strong parallels between ODBC and PEAR DB. First you connect to the
database, then you execute queries and fetch the results. You need to connect only
once within each script, and the connection is automatically closed when the script
ends.
The odbc_autocommit( ) function controls transactions. By default, changes to the
database (UPDATE, DELETE, and INSERT commands) take place as soon as the query is
executed. That’s the effect of autocommitting. Disable autocommits, however, and
changes will be visible to you but will be rolled back if the script ends without a
COMMIT SQL statement being executed.
Example 15-5 shows a script that lets the user enter a new record into the phone
database. The same script handles displaying the form, displaying the confirmation
Interacting with ODBC Data Sources | 371
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