PHP and IBM i - Database Alternatives

PHP and IBM i – Database Alternatives

Tony Cairns (adc@us.ibm.com)
Software Developer
IBM Systems & Technology Group, Systems Software

8 Copyright IBM Corporation, 2009. All Rights Reserved.
This publication may refer to products that are not currently
available in your country. IBM makes no commitment to make
available any products referred to herein.

Agenda
• Zend Toolkit
– Native I/O Calls
– Web Enabling DB2 with PHP using the i5 Toolkit
–
• DB2 Language Extensions
– SQL Compliant Syntax
•
• IBM DBi Storage Engine
•
•
•

© 2009 IBM Corporation

Web Enabling DB2 with PHP
Native I/O Calls


i5 Toolkit APIs

• Are shipped with Zend products
– Zend core for i5/OS
– Zend Platform for i5/OS
•
• Geared towards accessing i5 data and resources from PHP
– Similar in purpose to the IBM Toolbox for Java
•
• Note: the I5_COMD job must be running in the ZEND subsystem
– Use the Zend menu to start:
• GO ZENDCORE/ZCMENU
• Option 5 (Service Management menu)
• Option 8 (Start I5_COMD service)


PHP Toolkit for i5/OS – list of functions
• Connection management • Data retrieval • Native file access
–i5_connect – i5_fetch_array – i5_open
–i5_close – i5_fetch_assoc – i5_addnew
–i5_adopt_authority – i5_fetch_object – I5_edit
–i5_error – i5_fetch_row – I5_delete
–i5_errno – i5_cancel_edit
– i5_info
–i5_errormsg – i5_setvalue
– i5_field_len
» – i5_update
– i5_field_name
• Command calls – i5_range_from
– i5_field_scale
–i5_command – i5_range_to
– i5_field_type
» – i5_range_clear
• Program calls – i5_list_fields
– i5_num_fields – i5_data_seek
–i5_program_prepare
– i5_result – i5_seek
–i5_program_prepare_PCML
– i5_bookmark
–i5_program_call
–i5_program_close – i5_free_file
– i5_new_record
– i5_update_record
– i5_get_keys
–


PHP Toolkit functions
• System values • Job logs • User space
–i5_get_system_value –i5_jobLog_list –i5_userspace_crearte
» –i5_jobLog_list_read –i5_userspace_prepare
• Data areas –i5_jobLog_list_close –i5_userspace_get
–i5_data_area_prepare – –i5_userspace_put
–i5_data_area_receive • Active jobs –
–i5_data_area_send –i5_job_list • Data Queue
–i5_data_area_close –i5_job_list_read –i5_dtaq_prepare
– –i5_job_list_close –i5_dtaq_recieve
• Print/Get spooled file – –i5_dtaq_send
–i5_spool_list • Objects list –i5_dtaq-close
–i5_spool_list_read –i5_object_list –
–i5_spool_list_close –i5_object_list_read
–i5_spool_get_data –i5_object_list_close
–i5_spool_from_file –
–
–
•
–


Record-level access

• i5_open
– Pass in library/file and type of "open" mode
• I5_OPEN_READ, IT_OPEN_READWRITE, I5_OPEN_COMMIT, I5_OPENSHRRD,
I5_OPEN_SHRUPD

•
•
• i5_list_fields
– Get an array of the names of the fields in the file
–
• i5_fetch_row
– Get an array of the fields in a record, passing in which record to fetch
• I5_READ_SEEK (current)
• I5_READ_NEXT (default)
• I5_READ_PREV
• I5_READ_FIRST
• I5_READ_LAST


Record-level access: HTML code

• <form method="post" action=“i5_fetch.php">
•
• Library (schema): <input type="text" name="lib"><br>
•
• File (table): <input type="text" name="tbl"><br>
•
• <input type="reset"> <input type="submit"
value="Display records">
•
• </form>


Record-level access: PHP code
• // Get input data
• $dbfile = $_POST['tbl'];
• $dblib = $_POST['lib'];
•
• // Open the file
• $file = i5_open("$dblib/$dbfile", I5_OPEN_READ);
• if (!$file)
• die("Error while attempting to open file mode=READ");
•
• // Print a table row of field names
• $fields = i5_list_fields($file); // returns an array
• print "<table border=1 cellpadding=3><tr bgcolor=#CCCCCC>";
•
• // Parse the array
• foreach ($fields as $value) {
• print "<th>$value</th>";
•}
• print "</tr>n";



• // Print records
• $rec = i5_fetch_row($file, I5_READ_FIRST); // get array
• while ($rec) { // while there is a record...
• // Print each field in the array
• foreach ($rec as $value) {
• print “<td>$value</td>";
• }
• print "</tr>n";
• // Get next record
• $rec = i5_fetch_row($file, I5_READ_NEXT);
• } // loop
•
• print "</table>"; // finish off the table


Example Form and Output


Web Enabling DB2 with PHP
Using the i5 Toolkit


PHP Get Records (i5 toolkit SQL model)

• Recall from our previous function model_connect()

discussion that before any of the { global $MODEL;
$db_options = array(I5_OPTIONS_JOBNAME=>"DVDSEARCH");
APIs from the i5 toolkit can be $MODEL ['conn'] = i5_pconnect
( $MODEL ['database'],
used we must establish a $MODEL ['db_user'],
$MODEL ['db_password'],
connection to the i5 toolkit );
$db_options

daemon process (PGM- if (! $MODEL ['conn'])
{ model_error_i5("Connect fail");
EASYCOM job) return False;
}
• The i5_pconnect() API is being return model_chglibl();

used to establish a persistent NOTE: Each browser button click will
connection and avoid costly IBM i run back through the i5_pconnect()
startup and termination code; however since the connection is
associated in the cached for each Apache worker job the
i5_connect() and actual processing time is minimal.
i5_close() APIs.
• Establish a connection is a fairly NOTE: In this case each button click will
common activity so a site not find it’s way back to the same worker
common include comes in handy job (more on this later).

i5 toolkit browser clicks route to different Apache
jobs
• Persistent i5 connections means
that each “stateless” Apache job
will have a common connection
to the i5 toolkit
– This common connection will be
used by all PHP i5 toolkit
applications running, not a
single application or job
• Persistent connections does not
mean that each browser click will
return to the same job
– Do not attempt commit
transactions across multiple
browser clicks!!


i5_pconnect() results in many PGM-EASYCOM jobs

• Supplying a user-id and
password to the i5_pconnect()
call will spawn multiple PGM-
EASYCOM server processes
for each different user profile
specified
– This behavior is dependent on
the Apache user peak
demand
•
• It is good practice to limit the
number of “active” web profiles.
•
• A “private” connection can be
used for traditional “state full”
RPG applications (more on this
later)


i5_prepare() and i5_execute()
• The i5 toolkit API combination of i5_prepare() and i5_execute() allows
the DB2 engine to optimize and reuse SQL statements many times.
– This can provide improved performance on high volume web sites that
have many DB2 calls.
•
• The i5 toolkit SQL code shown on the following pages replaces the
RPG back-end.
•
• The same function names are used in the i5 toolkit SQL MVC as the i5
toolkit model function names (model_search)
– When we replace the model code with i5 toolkit SQL the view and control
code do not have to change (the 5250 code can also remain the
same)
Reminder: The i5 toolkit model used
APIs to call the RPG model.


i5 Toolkit SQL
code example (slide 1 of x)
<?php
function model_search($browsetype, $browse_title, $browse_actor, $browse_category, $limit_num, &$items)
{ global $MODEL, $categories;
if (!model_connect ())
{ False;
}
$items = array ( );
$prepare = null;
$sql = "";
switch($browsetype)
{ case 'title':
$sql .= "select * from products";
$sql .= " where TITLE like '%$browse_title%'";
$sql .= " FETCH FIRST $limit_num ROWS ONLY";
$prepare = i5_prepare($sql);
break;
case 'actor':
$sql .= " where ACTOR like '%$browse_actor%'";
break;
case 'category':
// oops did not plan ahead for this
for ($i=1;$i<=count($categories);$i++)
{ if ($categories[$i-1]==$browse_category)
{ break;
}
}


i5 Toolkit SQL code example (slide 2 of x)
$sql .= " where CATEGORY = $i";
break;
default:
break;
}
if (!$prepare)
{ model_error_i5("prepare $sql");
return False;
}
// execute prepared statement
$execute = i5_execute($prepare);
if (!$execute)
{ model_error_i5("execute");
return False;
}
// fetch the row data
$i=0;
while ($row = i5_fetch_assoc($prepare, I5_READ_NEXT))
{ array_push
( $items,
array
( $row["PROD_ID"],
$row["TITLE"],
$row["ACTOR"],
$row["PRICE"]
)
);
$i++;
}
if (!$i)
{ model_error_i5 ( "No DVDs found" );
return False;
}
return True;
}


DB2 for i5/OS Language Extensions


Accessing DB2/400
• Server/connection • Errors
– db2_bind_param
• Fetch
– db2_fetch_array – db2_conn_error
– db2_client_info
– db2_fetch_assoc – db2_conn_errormsg
– db2_close – db2_fetch_both – db2_stmt_error
– db2_connect – db2_fetch_object – db2_stmt_errormsg
– db2_cursor_type – db2_fetch_row • Column/Procedure
– db2_exec • Field information – db2_column_privileges
 db2_execute – db2_field_display_
size – db2_columns
 db2_prepare
– db2_field_name – db2_procedure_column
– db2_pconnect s
– db2_server_info – db2_field_num
– db2_procedures
– db2_statistics – db2_field_precision
– db2_special_columns
– db2_field_scale
• Result • Table information
– db2_field_type
– db2_free_result – db2_num_fields
– db2_field_width
– db2_next_result • Key information – db2_num_rows
– db2_result – db2_foreign_keys – db2_table_privileges
• Commit/Rollback – db2_primary_keys – db2_tables
– db2_autocommit • Statement
– db2_commit – db2_free_stmt documented online at php.net
All of these APIs are
– db2_rollback  - Preferred db2_ SQL statement execution APIs (performance)
• - Non-preferred db2_ SQL statement execution API


Server connection – db2_connect API

• There are few connections options in PHP
– db2_connect(“”,””,””) – local server
• The database connection job is create under the same user as the Apache httpd
server profile NOBODY (*USER).
•
– db2_connect(“*LOCAL", “SAM", “PASSWROD")– local server
• The database connection job is created under the user profile SAM/PASSWROD.
•
– db2_connect(“10.1.1.33", “SAM", “PASSWROD") – remote database
connection job is created under the user server
• The profile SAM/PASSWROD.
–
–

● Tip: Use WRKRDBDIRE to get the database name on the remote


i5 Toolkit vs. DB2 Extensions

• The i5 Toolkit represents functions for accessing native i5/OS resources
– The toolkit is specific to the Zend products for i5/OS
– The toolkit functions can only access local resources (i.e., resources on the same
i5/OS partition as Zend Core) unless you setup remote connections (such as
DDM) outside of the Zend Core environment.
– All i5 Toolkit functions begin with the characters “i5_”
• The DB2 functions represent an extension to the PHP language
– The DB2 extensions are starting to become part of the mainstream php language
offering and will be available on platforms other the i5/OS
– The DB2 extensions can access both local and remote DB2 resources through
established network connections
– All DB2 functions begin with the characters “db2_”


i5 Toolkit vs. DB2 Extensions

i5_*
I5_COMD

Zend Core I5/OS
Resource
PASE db2_*

i5/OS

TCP/IP db2_*

I5/OS
Resource

i5/OS


Anatomy of a Web-Enabled DB2 for i5/OS (via
PHP) application


Application Description

• We will take a look at a single PHP application.
•
• The application will create an employee information search and retrieval
form
•
• All of the following code would be saved in a single file (ex:
employee_update.php)
– As you will see, we can use HTML form fields to allow the application to re-
call itself for different functions within the application.


Employee Search Form

• When invoked (through a Web Browser) this code will generate a
blank web page with a title bar of “Employee Update –
employee_update.php”)

<html>
<?php
define("PAGE_TITLE", "Employee Update");
define("PHP_FILE_NAME", "employee_update.php")
?>
<title><?= PAGE_TITLE . " - " . PHP_FILE_NAME; ?></title>
<body>
<?php
?>
</body>
</html>


Employee Search Form

• The following block of code will cause the
Employee Search form to be displayed.
This block of code is inserted between
the <?php tag and the corresponding ?
> tag

/* Display the initial Employee Search form and the $_POST lastname field */
/* When the Search button is selected. */
print '<h1>Enter the first few characters of the employee records you' .
'wish to view/edit in the last name field.</h1>';
print '<h2>For example, "JO":</h2>';
print '<form action="employee_update.php" method="POST">';
print 'Last Name: <input type="text" name="lastname" /> <br />';
print '<input type="submit" name="action" value="Search" />';
print <'/form>';

• This block of code outputs in the HTML stream instructs for what is to be entered
into the form along with the HTML to generate the form information.


Search Action

• The following block of code implements the search function
– This function uses the values entered on the Employee Search Form to open the database and
perform the search action
– This block of code would be inserted between the <?php tag and the /* Display comment

/* Include System i connection information */
1 if ((include "../i5_properties.php") == false) {
echo("Problem encountered loading i5_properties.php include file");
}

/* Set up connection for each pass through this application */
2 $dbh = db2_connect($db, $user, $password);
if (!$dbh) :
3 die ("Problems connecting to the database.");
endif;

1. The if statement causes a separate PHP file that contains a number of
variable definitions for the program (including database name, user
credential information) to be included
2. The db2_connect() call is one of the calls from the DB2 for i5/OS
extensions – it establishes a connection to the database server and
returns a handle to the indicated database.
3. The if statement tests that a valid handle to the database was returned
and if not the application terminates (via the die language construct)


Database Query
• The next section of code performs the database query and places
the results on the Employee Search Results form.
– The code would be placed between the </form> line and the
second ?> php end} tag
else
{
/* Query file using input from form and deliver results to client */
/* Construct SQL statement, using lastname as the search substring */
1 $sql = 'select * from i5schema.employee where lastname like ''
.$_POST["lastname"]. '%'';
/* Execute the DB2 SQL statement, place results into $stmt */
2 $stmt = db2_exec($dbh, $sql, array('cursor' => DB2_SCROLLABLE));
/* Print Employee Search Results header and table setup */
print '<h1>Employee Records On System i starting with ' .
$_POST["lastname"]. '</h1>';
3 print '<br><table border=1 cellpadding=5 cellspacing=5>';
/* Iterate through result set, printing one table line per */
/* record returned. Note that the customerNumber field will */
/* be an "active field" which will $_GET the customerNumber */
/* and reinvoke the employee_update.php application*/

1. This statement assigns an SQL select statement to the $sql variable. The SQL
statement includes values entered on the Employee Search from
2. The db2_exec() statement causes the SQL statement to be executed against the
database that was opened previously with the db2_connect() function call.
3. The print statements will output in the HTML stream for the first part of the
search results form which includes a header line indicating what records are
being displayed as well as a table that will contain the returned records

Database 4
while ($row = db2_fetch_array($stmt))
{
if (!$row=="") {
Query $customerNumber = $row[0];
$customerName = $row[3];
$customerFirst = $row[1];
$workdept = $row[4];
$job = $row[7];
$salary = $row[11];
print '<tr><td align=center><a
5 href=employee_update.php?customerNumber=' .
$customerNumber . '>' . $customerNumber .
'</a><td>'. $customerName.'<td>'.
$customerFirst.'<td>'. $workdept.'<td>'.
$job.'<td>'. $salary.'</td></tr>';
}
}
/* Close table */
print '</table><br>';
6 /* Print the DB2 SQL statement which was executed - Informational */
print "<p>Echo of dynamically-built sql: ".$sql."</p>";
}

4. The while loop iterates through the records returned by the db2_exec() function call (as
represented by the $stmt variable) and outputs them into the HTML table.
• Each time through the loop the db2_fetch_array() function will return an array of values
representing a row in the result set
5. Notice that the employee number ($customerNumber) is output as an actionable tag (i.e., it
will be a selectable link on the HTML page)
• This is accomplished through the ‘href’ statement which causes this php application to be re-called
when the tag is selected
6. The HTML tag to close the HTML table is output along with outputting the SQL statement
that was executed.


Database Query Notes
• Using the db2_exec() statement to insert PHP variable values into an
SQL statement can be considered a security exposure.
– Rather then using the db2_exec() statement the db2_prepare() statement
could be used to prepare an SQL statement with parameter markers for
input values.
– Then the db2_execute() statement could be used rather then the
db2_exec() statement to pass in the input values.
• When the PHP file is invoked (from a Web Browser) the search form is
displayed. Entering data into the Last Name field and selecting the
[Search] button causes the Query code to be executed and the results
to be displayed in the web form


Database Query – Employee Record Edit

• This code will determine which record to place on the Edit form. The code
is invoked when an employee number is selected from the search results
window
– This code would be placed between the $action = $_POST[“action”]
and the if(!$action) lines

1 $customerNumber = $_GET["customerNumber"];2
/* Determine which form to display based upon the state of the
application */
2 if ($customerNumber == "") {

1. The employee number selected on the search results form is retrieved from the
URL and assigned to the $customerNumber variable
2. The test of the $customerNumber field is performed to see if this block of code
was reached after an employee number was selected from the search results
window.
• Remember that this PHP code generates both the Employee Search as well as the
Employee Search Results pages


Edit Record
• The following code displays the values of a record and allows the user to edit
those values
– This code would be placed between the bracket (}) line and the second ?> php tag
} else { /* Edit the selected customer number record */
/* Construct SQL statement, using customerNumber to select the record */
$sql = 'select * from i5schema.employee where empno = ''
1 .$_GET["customerNumber"]. ''';
/* Execute the DB2 SQL statement, place results into $stmt */
2 $stmt = db2_exec($dbh, $sql, array('cursor' => DB2_SCROLLABLE));
/* Place the field information returned into array $row */
$row = db2_fetch_array($stmt);
3 /* If there is data, move information from result array into fields */
/* which will be used for screen display */
if (!$row=="") {
$customerNumber = $row[0];
4 $customerName = $row[3];
$customerFirst = $row[1];
$workdept = $row[4];
$job = $row[7];
$salary = $row[11];
}

1. The select statement establishes the query using the customer number that the
user selected from the HTML form
2. The db2_exec() function call executes the query
3. The db2_fetch_array() function call retrieves an array of fields values from a
record in the return set from the db2_exec() function call
4. The if statement tests to ensure that a record was returned from the
db2_fetch_array() call. If a record was returned, local variables are used to
tore the field values.

Edit Record
/* Display the Employee Edit form and $_GET all fields */
/* when Update button is selected. */
print '<h1>Edit an Employee record:</h1>';
print '<form action="employee_update.php" method="GET">';
print 'Customer Number: <input type="text" name="customerNumber"
value="'.$customerNumber.'" /> <br />';
print 'Last Name: <input type="text" name="customerName"
value="'.$customerName.'" /> <br />';
print 'First Name: <input type="text" name="customerFirst"
value="'.$customerFirst.'"/> <br />';
5 print 'Work Department: <input type="text" name="workdept"
value="'.$workdept.'"/>';
print 'Job Type: <input type="text" name="job" value="'.$job.'"/> <br />';
print 'Salary: <input type="text" name="salary" value="'.$salary.'"/> <br
/>';
print '<input type="submit" name="action" value="Update" /><a
href=employee_update.php?customerNumber=' .
$customerNumber .'&customerName='
.$customerName.'&customerFirst='.$customerFirst.'&workdept='.
$workdept.'&job='.$job.'&salary='.$salary.'&action='.$submit.'></a>';
print '</form>';
}

5. A series of print statements are used to output text labels as well as the contents
of the returned record


Edit Record – Notes

• The print ‘<form’> along with the print ‘<input> line (italicized in the code
for emphasis) will cause the program to place the “Update” action onto
the URL line when the Update button is selected
– Each of the field values are also placed into the URL string.
– This causes the application to “call” itself again.
– The URL string values are retrieved using the $_GET function and then
used in the SQL update call (coming up)
• When the PHP program is invoked and a record is searched for and
selected the Results form will display the Employee Edit Record form
with the values from the selected record


Record Update

• This code is invoked when the [Update] button is selected from the Edit
page.
• The code updates the DB2 for i5/OS table using the user modified fields.
• Once the record has been updated an HTML form is output with the SQL
statement along with an indication of whether or not the update was
successful.
• The first section of code determines the state of the application, that is has
the user selected the [Update] button from the Edit page.
• The following code would replace the $action = $_POST[“action”] line of
code which is just prior to the $customerNumber =
$_GET[“customerNumber’] statement

$action = $_GET["action"];
/* if no value from $_GET, try $_POST */
if (!$action) {
$action = $_POST["action"];
}


Record Update

• The section of code that resembles the following

}
} else { /* Edit the selected customer number record */

• Would be changed to resemble the following (i.e., remove the beginning
close bracket on the else statement
}
else { /* Edit the selected customer number record */


Record Update

• The following block of code would be placed before the else { /* Edit
the selected customer number record */ statement
1 } else { /* Update Employee table, or edit the selected customer record */
if ($action == "Update") {
$sql = 'update i5schema.employee set lastname = 2
''.$_GET["customerName"].'','.
' firstnme = ''.$_GET["customerFirst"].'','.
2 ' workdept = ''.$_GET["workdept"].'','.
' job = ''.$_GET["job"].'','.3
' salary = '.$_GET["salary"].
' where empno = '' .$customerNumber.''';4
3 $result = db2_exec($dbh, $sql);

1. The if statement determines whether or not the user requested the Update action
from the Edit Record form.
• If the update action was invoked then the remaining code is executed
2. The assignment statement generates the SQL update statement using values
passed from the calling form
3. The db2_exec() function call executes the SQL update statement returning the
results into the $result variable.


Record Update

if (!$result) {
4 echo '<p>There was a problem inserting the user into the
database.</p>';
print '<p>Echo of dynamically-built sql:<br>'.$sql.'</p>';5
} else {
print '<h1>Update Successful</h1>';5
5 print '<form action="employee_update.php" method="POST">';
print '<p>Echo of dynamically-built sql:<br>'.$sql.'</p>';
print '<input type="submit" name="action" value="Continue" /><a
href=employee_update.php></a>';
print '</form>';
}
}

4. The if statement tests the result returned from the db2_exec() call.
• If an error was encountered by the update statement an error message is output to the
HTML form.
• If the update statement was successful a success message is output along with the
actual SQL statement that was executed by the db2_exec() function call.
5. The <form> line along with the <input> line causes the program to place the
“Continue” action onto the URL string when the [Continue] button is selected.
The program will then be automatically re-invoked.

• In addition to the above code a line containing a closing bracket (}) would need to
be placed before the second ?> php end tag at the bottom of the application


Record Update – Notes Page

• Now when the application is invoked, searching for a set of records,
selecting a record from the returned set, edit the values and selecting
the [Update] button will cause the record to be updated and a web page
similar to the following to be displayed


Continue

• The final piece of code that we need to look at is the code that processes
selection of the [Continue] button.
• When the [Continue] button is selected, the application will be reset back
to the Employee Search form
• In the following section of code:
/* Determine which form to display based upon the state of application */
if ($customerNumber == "") {
if (!$action) {

• The if (!$action) line would be replaced with the following
if ((!$action) or ($action == "Continue")) {

• The check for the “Continue” action will cause the Search form to be
displayed when the [Continue] button is selected from the Update
database form.


Why MVC
• Recall that we are using the MVC model to separate out the model, view,
and controller components of the program
– This makes it easy to replace one component without affecting the others.
• In this example, the same PHP view/control code as in the previous i5 call
RPG program example is used.
– Now a different include_once for the MVC ibm_db2 model is used

<?php
define('APP_BASE_DIR', '/www/zendcore/htdocs/qiwikiCode/');
include_once APP_BASE_DIR.'101Config.php'; /* Site: site configuration */
include_once APP_BASE_DIR.'101Connectdb2.php'; /* Model: ibm_db2 connect */
include_once APP_BASE_DIR.'101DB2Model.php'; /* Model: ibm_db2 SQL */
include_once APP_BASE_DIR.'101HtmlView.php'; /* View: plain old generated html */
include_once APP_BASE_DIR.'101HtmlControl.php'; /* Control: main loop html forms */
?>

• In this example, the RPG back-end (the model) is being replaced with PHP
ibm_db2
– A new DB2 model include_once is used to handle the connections to
ibm_db2


PHP Get Records (ibm_db2 model)
Establish a connection
• In an earlier module we looked at the i5_toolkit calls which uses the
i5_connect (and i5_pconnect) to connect to the PGM-EASYCOM jobs.
– A daemon approach is used that monitors a socket for in-coming
connections that are started by the Zend core menus and subsystems.
•
• The ibm_db2 language extension uses in-line calling and/or special
memory shipping if going between QSQ server jobs and Apache worker
jobs.
•
• Simply put, different connection methods are used by these two facilities
as then come from different sources. The ibm_db2 language extension
comes from IBM while the i5_toolkit calls comes from another PHP
vendor.


PHP Get Records (ibm_db2 model)
Using db2_pconnect vs db2_connect
• The db2_pconnect() API supports function model_connect()
{ global $MODEL;
persistent connections $db_options = array("i5_naming"=>DB2_I5_NAMING_ON);
$MODEL ['conn'] = db2_pconnect
• The db2_connect() API does not ( $MODEL ['database'],
$MODEL ['db_user'],
support persistent connections $MODEL ['db_password'],
$db_options
• Use of the db2_pconnect() API );
if (! $MODEL ['conn'])
can improve performance of web- { model_error_db2("Connect failed");
sites when they are experiencing }
return False;

heavy user web demand return model_chglibl();
}

• Notice the array(“i5_naming”=>DB2_I5_NAMING_ON)
– libl changes via db2_set_option(“i5_libl”=>) will work with unqualified table
names
– It is likely that for stored procedure calls to an RPG program, the RPG program would
also likely need the library list set.Use of persistent connections is absolutely
required if the site services multiple requests
Tip! Setting DB2_I5_NAMING_ON
per second.
for the whole set simply works better
on IBM i. Mixing
DB2_I5_NAMING_ON/OFF almost The php.ini configuration file can be updated
always leads to problems on the site to force all db2_connect() calls to use
db2_pconnect() instead

db2_connect() browser clicks route to different
Apache jobs
• The use of a persistent db2
connection only means that each
“stateless” Apache job will have
a common connection to db2
– This common connection will be
used by all PHP ibm_db2
applications running, not just
a single application or “job”.
•
• Persistent connections does not
mean that each browser click will
return to the same job
Tip! Do NOT attempt
db2_commit() transactions across
multiple browser clicks!!!


db2_pconnect() results in many QSQ jobs

• Supplying a user-id and password
to the db2_pconnect() call will
spawn a QSQ db2 server
process for each different user
profile specified for each Apache
worker job

Tip! It is a good practice to limit the
number of “active” web profiles.

NOTE: Once the QSQ job has been Tip! Mixing db2_pconnect(“”,””,””)
spawned there will be little and db2_pconnect(“*LOCAL”,”uid”,”pwd”)
difference between profiles can lead to unpredictable results – pick a
(assuming that db2_pconnect() profile or two to handle web clients and
was used) stick with those.


What about db2_connect?

• Recall from the previous slide that a QSQ db2 server process is spawned
for each different user profile for each Apache worker job
– In the case of db2_connect, the QSQ job starts and stops with each
db2_connect() and db2_close() call.
– This is a performance degredation over the use of the persistent
db2_pconnect() call – especially for those sites with heave traffic and
many requests per second.
•


db2_prepare() and db2_execute() vs. db2_exec()

• Use of the db2_prepare() and db2_execute() API combination
allows the DB2 engine to optimize and reuse SQL statements
many times.
– Use of these APIs on high volume web sites can provide a
performance boast over db2_exec()
•
• The ibm_db2 code shown on the next slides replaces the RPG
back end.
– The MVC model function names have been kept exactly the same
as the i5 toolkit model function names (model_search)
– When the model code is replaced with ibm_db2 the view and
control model do not change (the 5250 code will also remain the
same)


db2_prepare() and db2_execute()
Code Sample (slide 1 of 2)
<?php
function model_search($browsetype, $browse_title, $browse_actor, $browse_category, $limit_num, &$items)
{ global $MODEL, $CATEGORIES;
if (!model_connect ())
{ return False;
}
$link_id = $MODEL ['conn'];
$items = array ( );
$prepare = null;
$sql = "";
switch($browsetype)
{ case 'title':
$sql .= " where TITLE like '%$browse_title%'";
$prepare = db2_prepare( $link_id, $sql);
break;
case 'actor':
$sql .= " where ACTOR like '%$browse_actor%'";
break;
case 'category':
// oops did not plan ahead for this
for ($i=1;$i<=count($CATEGORIES);$i++)
{ if ($CATEGORIES[$i-1]==$browse_category)
{ break;
}
}
$sql .= " where CATEGORY = $i";
break;


Code Sample (slide 2 of 2)
default:
break;
}
if (!$prepare)
{ model_error_db2("prepare $sql");
return False;
}
// execute prepared statement
$execute = db2_execute($prepare);
if (!$execute)
{ model_error_db2("execute");
return False;
}
// fetch the row data
$i=0;
while ($row = db2_fetch_assoc($prepare))
{ array_push
( $items,
array
( $row["PROD_ID"],
$row["TITLE"],
$row["ACTOR"],
$row["PRICE"]
)
);
$i++;
}
if (!$i)
{ model_error_db2 ( "No DVDs found" );
return False;
}
return True;
}


Another Code Sample – Populate database table
• In this example, db2_prepare() and db2_execute() are being used to
populate the database table
// Populate the products table
$products =
array
( // 1= Action
array(1, 1, 'Death Car', 'Brad Baldwig', 3.22, 1),
array(2, 1, 'Super Car', 'Gwen Midriff', 3.22, 1),
// 2 = Animation
array(3, 2, 'Happy Frog', 'Fred Flimflam', 6.22, 1),
array(4, 2, 'Happy Toad', 'Fred Flinflam', 6.22, 1),
// 3 = Horror
array(5, 3, 'Creek of Doom', 'Chris Wock', 25.99, 1),
array(6, 3, 'River of Doom', 'Chris Wock', 25.99, 1),
// 4 = Sci-Fi
array(7, 4, 'Alien of Troy', 'Chris Wock', 25.99, 1),
// 5 = Sports
array(8, 5, 'Runner Beware', 'Bruce Henpecked', 5.31, 1),
// 6 = Travel
array(9, 6, 'Ships, ships, ships','Bear Greenwood', 3.33, 1),
);
$insert = "INSERT INTO $lib.PRODUCTS";
$insert .= " (PROD_ID, CATEGORY, TITLE, ACTOR, PRICE, SPECIAL)";
$insert .= " VALUES (?,?,?,?,?,?)";
$stmt = db2_prepare($conn, $insert);


Another Code Sample – Populate database table
• In this example, db2_prepare() and db2_execute() are being used to
populate the database table

if($stmt)
{ foreach($products as $row)
{ $r = db2_execute($stmt, $row);
if (!$r)
{ die("<br>bad insert ".db2_stmt_errormsg() );
}
else
{ $nrows = db2_num_rows($stmt);
echo ("<br>INSERT $nrows row data = ".implode(",", $row) );
}
}
}


API Level Check

• A quick level check on some of the APIs that we’ve talked about:
•
• The db2_pconnect() API should be used over the db2_connect()
API as db2_pconnect() supports persistent connections:
$conn = db2_pconnect("","",""); // persistent connect

• The db2_prepare() and db2_execute() APIs should be used over
the db2_exec() API for optimization and reuse of SQL statements
$prep = db2_prepare($conn,"sql"); // prepare statement
$retc = db2_execute($prep); // execute prepared statement


Methods (APIs) for fetching data

• There are a number of choices in PHP for fetching data:

db2_fetch_array() Returns an array, index by column position, that
represents a row in a result set. Column indexing
starts at 0.
db2_fetch_assoc() Returns an array, indexed by column name, that
represents a row in a result set.
db2_fetch_both() Returns an array, indexed by both column name and
position, that represents a row in a result set. Keep in
mind that the row returned by db2_fetch_both() will
require more memory than the single-indexed arrays
returned by db2_fetch_assoc() or db2_fetch_array()
db2_fetch_object() Returns an object in which each property represents
a column returned in the row fetched from a result set.


Methods (APIs) for fetching data
• There are a number of choices in PHP for fetching data:
while ($row = db2_fetch_array($prep)) // one syscall per row (SQLBindCol)
{ $name = $row[0];
$breed = $row[1];
}

while ($row = db2_fetch_assoc($prep)) // one syscall per row (SQLBindCol)
{ $name = $row["NAME"];
$breed = $row["BREED"];
}

while ($row = db2_fetch_both($prep)) // one syscall per row (SQLBindCol)
{ $name = $row[0];
$breed = $row[1];
// -- or –
$name = $row["NAME"];
$breed = $row["BREED"];
}

while ($row = db2_fetch_object($prep)) // one syscall per row (SQLBindCol)
{ $name = $row->NAME;
$breed = $row->BREED;
}

NOTE: In all these different All of the db2_fetch options discussed bring the
examples, $prep represents the contents of the entire row back to PHP in one
resource that contains the result set. system call via the SQLBindCol interface


What about db2_fetch_row() / db2_result()

• Second-tier APIs such as $conn = db2_pconnect("","",""); // persistent connect

db2_fetch_row() and $stmt = db2_prepare($conn,"sql"); // prepare statement
$retc = db2_execute($prep); // execute prepared statement
db2_result() should be used { $name = db2_result($stmt, 0); // another syscall here
while (db2_fetch_row($stmt)) // syscall here

only when other fetch }
$breed = db2_result($stmt, 1); // another syscall here

options fail.
•
• A performance issue with db2_fetch_row() / db2_result() will be
encountered
– Fields are retrieved by systems calls all the way through the i5 kernel via
SQLGetData
•


Avoid meta data APIs
• The following ibm_db2 APIs should be used as a last option as of the DB2 meta
data APIs result in a heavy performance impact
– If possible avoid use these in the main application flow path

• db2_client_info • db2_get_option
• db2_column_privileges • db2_num_fields
• db2_columns • db2_num_rows
• db2_cursor_type • db2_primary_keys
• db2_escape_string • db2_procedure_columns
• db2_field_display_ size • db2_procedures
• db2_field_name • db2_server_info
• db2_field_num • db2_set_option
• db2_field_precision • db2_special_columns
• db2_field_scale • db2_statistics
• db2_field_type • db2_table_privileges
• db2_field_width • db2_tables
• db2_foreign_keys
NOTE: Detailed information on this APIs can be
found in the online PHP manual
(http://www.php.net/manual/en


IBMDB2i Storage Engine


Storage Engines
•
• A key strength of MySQL is it’s pluggable storage architecture.
• This architecture allows you to select a specialized storage engine for a particular
application need
• Different storage engines can be used for different tables within the same
database schema

• Key differentiations
– Concurrency/Locking
– Transaction Support
– Physical Storage
– Index Support
– Memory Caches
– Performance Aids


Storage Engines

• Two tier approach
– Upper tier includes the SQL parser and optimizer
– Lower tier comprises a set of storage engines
•
• The SQL tier is free of dependencies on which storage engine manages any
given table
•
• Clients do not need to be concerned about which engines are involved in
processing SQL statements.


Integrating MySQL with DB2
• DB2 Storage Engine for MySQL supports open source applications while
simplifying data management
– Applications written to MySQL, but data stored in DB2
– One database to manage, backup, and protect
• Integrates access to MySQL data from RPG,
DB2 Web Query, …

Application Written to MySQL MyISAM Specialty
MySQL (Example server Storage storage
SugarCRM) Engine engines

DB2i Storage DB2
alter table tablename ENGINE=IBMDB2i Engine storage
engine


IBMDB2i – the newest MySQL storage engine
• Developed to allow existing MySQL-based applications to use DB2
for i for the data store.
• Only general-purpose storage engine designed to allow access to
data from outside of MySQL
• Fully-featured, it implements all applicable storage engine
operations (some occasional restrictions apply)
• Can be used as a drop-in replacement with most web applications
• Distributed and supported
by MySQL Existing PHP New RPG
Application Application

MySQL
IBMDB2I

DB2 for i


Leveraging MySQL Data with DB2 Web Query
• SugarCRM is a PHP application
written to MySQL
DB2 Web
• DB2 Storage Engine enables SugarCRM
Query
SugarCRM data to be stored
Writes to
in DB2 Accesses
MySQL Data
• DB2 WebQuery can access
SugarCRM data Data stored in

• Using DB2 Web Query SDK and DB2 for i
Report Broker you can integrate
reporting into SugarCRM


Storage Engine Comparison
• Comparison of features between popular MySQL Storage Engines
MyISAM InnoDB IBMDB2I
Usage Fastest for read heavy Fully ACID compliant Fully ACID compliant;
applications transactions data visible
externally
Locking Large-grain table Multi-versioning, row- Row-level locking
locks, no non-locking level locking
reads
Durability Table recovery Durability recovery Durability recovery

Supports NO YES YES
Transactions
Supports foreign keys NO YES YES

Allows access NO NO YES
through DB2 for i
interfaces Storage Engine Also supports
• DB2
 Multiple character sets (ASCII, Far East, and Unicode)
 All MySQL replication configurations
 All widely-used data types (including LOB-based)
•


Getting started with IBMDB2I
• Requirements:
– IBM i 5.4 or later
– MySQL version 5.1 for IBM i (IBMDB2I plugin is included by default)
– Enabling PTFs (PTF numbers still pending)
•
• Starting MySQL and installing the IBMDB2I storage engine plugin--
just three easy steps
1. Start the MySQL server
• bin/mysqld_safe &
2. Start a client connection
• bin/mysql –u root
3. Install the plugin (requires appropriate MySQL user authority)
• INSTALL PLUGIN ibmdb2i SONAME “ha_ibmdb2i.so”;
•
• Now MySQL tables can be created directly into DB2
– CREATE TABLE test.t1 (i INT) ENGINE=ibmdb2i;
•


How does it work?
• An SQL statement on an IBMDB2I table is sent to the MySQL server.
• The server parses and optimizes the statement.
– No DB2 optimization involved

• The IBMDB2I storage engine is called by the server to perform operations
associated with the statement.
• IBMDB2I passes the operation to the QSQSRVR job associated with the
MySQL application connection
– DDL operations (CREATE TABLE, ADD INDEX, etc.) are re-constructed as DB2 SQL statements and
executed.
– I/O (read/insert/delete/update) is done row-by-row via a native I/O interface

• Results are returned to the server and then to the client.
•

Client MySQL QSQSRVR

Client IBMDB2I QSQSRVR


Usage Notes
• Most MySQL identifiers are stored in DB2 with outer quotes to preserve case
sensitivity.
– create table db1.sales (orderno int) engine = ibmdb2i;
– The above creates the DB2 table ”sales” in schema “db1”.
•
• DB2 triggers, constraints, and indexes can be added outside of MySQL but are not
used by MySQL.
•
• Errors are mapped to MySQL errors when possible.
•
• However, DB2-specific errors are often reported as messages in the joblog of the
corresponding QSQSRVR job. The MySQL error log contains detailed
information about the error and the job (when possible).
•
• Security on DB2 tables is handled by the normal IBM i and DB2 mechanisms
– All DB2 tables accessed by IBMDB2I are accessed under the profile used to start the mysqld
program.
– Existing MySQL user security mechanisms control access to the tables via MySQL. MySQL users are
distinct from IBM i user profiles.
•


Getting MySQL to Recognize Existing DB2 tables

• The IBMDB2I storage engine does not recognize DB2 tables and indexes that are
created outside of MySQL
– The storage engine does not have the ability to auto-detect existing DB2 tables
•
• To enable MySQL to access an existing DB2 table, need to dump the table definition
& data from DB2 and create the table definition & data in MySQL
– There are data attributes and features in DB2 that are not supported in MySQL
•
• Example Steps
1. Generate the Data Definition Language from the DDS. This is done through the
QSQGNDDL API
2. Scrub the resulting DDL to make it compliant with MySQL
3. Dump the records from the DB2 table into a CSV file. This is done using the copy from
import file (CPYFRMIMPF) command.
4. Using the MySQL command ‘mysqldump’ to import the table definition. Make sure that
you have specified the DB2i storage engine
5. Use the MySQL command ‘LOAD DATA INFILE’ to load the data into the MySQL data.
Make sure that you have specified the DB2i storage engine


Using the DB2 Storage Engine
• --default_storage_engine=ibmdb2i
– Causes tables to be created with IBMDB2I if no engine is explicitly specified. Useful when
installing third party applications. The default storage engine is MyISAM otherwise.
–
• --ibmdb2i_rdb_name=xxxxxx
– Causes IBMDB2I to use the specified RDB. Only tables in this RDB can be used when this
option is specified. Default is QSYS.
–
• --ibmdb2i_transaction_unsafe=0/1
– Specifies whether transactions should be respected. Setting this to 1 causes IBMDB2I to
approximate MyISAM transactional behavior. Default is 0.
–
• The storage engine associated with a table can be switched at any time
– As easy as ‘ALTER TABLE myisamtable ENGINE=ibmdb2i;’
– Causes all data to be copied over during the alter.
– Makes moving existing MySQL web app data into DB2 trivial.
•


Expanding Access To Data
ILE Applications
(RPG, Cobol, etc)

DB2
server*
DB2
storage

IBMDB2I
AMP Stack for i

Apache
PHP
MySQL
IBM i

* Leverage IBM i functions such as
journaling, SAV/RST and DB2 Web Query

PHP and IBM i - Database Alternatives

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