PHP 5/MySQL Programming- P90 potx

$fieldName $valList HERE; } else { //it’s an ordinary field.. The INSERT statement that this function creates uses NULL as the primary keyval-ues for that field and send an appropriate

global $dbConn;

$output = “”;

//process a query just to get field names

$query = “SELECT * FROM $tableName”;

$result = mysql_query($query, $dbConn);

$output = <<<HERE

<form action = “processAdd.php”

method = “post”>

<table border = “1”>

<tr>

<th>Field</th>

<th>Value</th>

</tr>

HERE;

$fieldNum = 0;

while ($theField = mysql_fetch_field($result)){

$fieldName = $theField->name;

if ($fieldNum == 0){

//it’s the primary key field It’ll be autoNumber

$output = <<<HERE

<tr>

<td>$fieldName</td>

<td>AUTONUMBER

<input type = “hidden”

name = “$fieldName”

value = “null”>

</td>

</tr>

HERE;

} else if (preg_match(“/(.*)ID$/”, $fieldName, $match)) {

//it’s a foreign key reference Use fieldToList to get

//a select object for this field

$valList = fieldToList($match[1],$fieldName, 0, “name”);

$output = <<<HERE

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<td>$fieldName</td>

<td>$valList</td>

</tr>

HERE;

} else { //it’s an ordinary field Print a text box

$output = <<<HERE

<tr>

<td>$fieldName</td>

<td><input type = “text”

name = “$fieldName”

value = “”>

</td>

</tr>

HERE;

} // end if

$fieldNum++;

} // end while

$output = <<<HERE

<tr>

<td colspan = 2>

<input type = “hidden”

name = “tableName”

value = “$tableName”>

<input type = “submit”

value = “add record”>

</td>

</tr>

</table>

</form>

HERE;

return $output;

} // end tToAdd

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The INSERT statement that this function creates uses NULL as the primary key

val-ues for that field and send an appropriate key Any field not recognized as a

primary or foreign key will have an ordinary textbox.

Processing an Added Record

The tToAdd()function sends its results to processAdd.php, which reorganizes the

function procAdd($tableName, $fields, $vals){

//generates INSERT query, applies to database

global $dbConn;

$output = “”;

$query = “INSERT into $tableName VALUES (“;

foreach ($vals as $theValue){

$query = “‘$theValue’, “;

} // end foreach

//trim off trailing space and comma

$query = substr($query, 0, strlen($query) - 2);

$query = “)”;

$output = “query is $query<br>\n”;

$result = mysql_query($query, $dbConn);

if ($result){

$output = “<h3>Record added</h3>\n”;

} else {

$output = “<h3>There was an error</h3>\n”;

} // end if

return $output;

} // end procAdd

of tToAdd() This insert is passed to the database and the user receives a report

about the insertion attempt’s outcome.

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Building a List Box from a Field

pattern In both cases, I needed to build a list that allows the user to select a key value based on some other field in the record This list should be set so any value

function takes four parameters and uses them to build exactly such a list. function fieldToList($tableName, $keyName, $keyVal, $fieldName){

//given table and field, generates an HTML select structure

//named $keyName values will be key field of table, but

//text will come from the $fieldName value

//keyVal indicates which element is currently selected

global $dbConn;

$output = “”;

$query = “SELECT $keyName, $fieldName FROM $tableName”;

$result = mysql_query($query, $dbConn);

$output = “<select name = $keyName>\n”;

$recNum = 1;

while ($row = mysql_fetch_assoc($result)){

$theIndex = $row[“$keyName”];

$theValue = $row[“$fieldName”];

$output = <<<HERE right now, theIndex is $theIndex and keyVal is $keyVal

<option value = “$theIndex”

HERE;

//make it currently selected item

if ($theIndex == $keyVal){

$output = “ selected”;

} // end if

$output = “>$theValue</option>\n”;

$recNum++;

} // end while

$output = “</select>\n”;

return $output;

} // end fieldToList

The fieldToList()function begins by generating a query that returns all records

query As I step through all records, I see if the current record corresponds to the

$keyValparameter If so, that element is selected in the HTML.

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Creating a Button That

Returns Users to the Main Page

To simplify navigation, I added a button at the end of each PHP program that

variable, which is indicated at the top of the library.

function mainButton(){

// creates a button to return to the main program

global $mainProgram;

$output = <<<HERE

<form action = “$mainProgram”

method = “get”>

<input type = “submit”

value = “return to main screen”>

</form>

HERE;

return $output;

} // end mainButton

Summary

flex-ible design that you can easily update and modify This system can accept

modi-fications to the underlying database and can be adapted to an entirely different

data set with relatively little effort

Although you didn’t learn any new PHP syntax in this chapter, you saw an

sim-plify coding of complex systems and how to build a library file with utility

routines You learned how to write code that can be adapted to multiple data sets

and code that prevents certain kinds of user errors You learned how to build

pro-grams that help tie together relational data structures The things you have

learned in this chapter form the foundation of all data-enabled Web programming,

which in turn form the backbone of e-commerce and content-management systems.

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