Trying to print a report from SQL Database? - php

Question

Trying to generate a report form data base to be exported as an excel file, but I keep getting 0 results when there is data in the database. Can anyone take a look at the code and let me know what I have wrong. the code needs to go into a server that is running php 5.4+ from 4+
<?php
//set date
$date = date("m/d");
$course_report = $_POST['course_report'];
$course_info = explode('~',$course_report);
$course_info[0]; // course_id
$course_info[1]; // course_date
$select = "SELECT DISTINCT * FROM registrants WHERE (paid='Y' AND course_id = '$course_info[0]' AND course_date = '$course_info[1]')";
$result = mysqli_query($dbc, $select);
// first get the header row
while($row = mysqli_fetch_assoc($result)) {
$course = $row['course'];
$coursedate = $row['course_date'];
$export = mysql_query($select);
$fields = mysql_num_fields($export);
}
// Get header
$fields = isset($_POST['fields']);
for ($i = 0; $i < $fields; $i++) {
$header .= mysqli_field_name($export, $i) . "\t";
}
// Then get all the rows of data
$export = isset($_POST['export']);
while($row = mysqli_fetch_row($result)) {
$line = '';
foreach($row as $value) {
if ((!isset($value)) OR ($value == "")) {
$value = "\t";
} else {
$value = str_replace('"', '""', $value);
$value = '"' . $value . '"' . "\t";
}
$line .= $value;
}
$data .= trim($line)."\n";
}
$data = isset($_POST['data']);
$data = str_replace("\r","",$data);
// Check for blank data set
if ($data == "") {
$data = "\n(0) Records Found!\n";
}
// end building the data
$header = isset($_POST['header']);
$course = isset($_POST['course']);
$file_name = $course . "_downloaded_" . $date;
header("Content-type: application/x-msdownload");
//header("Content-Disposition: attachment; filename=Registrar_101.txt");
header("Content-Disposition: attachment; filename=$file_name.xls");
header("Pragma: no-cache");
header("Expires: 0");
print "$header\n$data";
// }
?>

Answer 1

This says it's only supposed to get one row, but it's actually going to get all rows.
// first get the header row
while($row = mysqli_fetch_assoc($result)) {
$course = $row['course'];
$coursedate = $row['course_date'];
$export = mysql_query($select);
$fields = mysql_num_fields($export);
}
Then for each row you're inexplicably re-exectuing the query with mysql_query()
and at this point I've stopped looking because you really need to clean up the logic here if the rest of the script is going to make any sense at all.

Answer 2

I'm not sure what you think is happening under "first get the header row". The query is retrieving records from the Registrants table. Where do you think a "header row" is coming from? Are you thinking that you are going to get a row back from the query with the column headers, i.e. the names of the fields? If so, that's not how it works.
Then within this loop you re-execute the query for every record. Why? What does that accomplish? Then you get the count of the number of fields from this inner query and put it in $fields. But you never use this value. After the loop, you promptly overwrite it.
Do you understand that isset() returns true or false? You seem to think it returns a string.
$_POST gets a value that was submitted on a form from a web page. You seem to be thinking that it's going to give you values from your query or something.
I'm not sure exactly what you're trying to accomplish, but I think the core of your program should look something like this:
<?php
//set date
$date = date("m/d");
$course_id = $_POST['course'];
$course_date = $_POST['course_date'];
// You really should use mysqli_real_escape_string to escape input strings,
// but let's skip that point for now
// Also, it's generally bad form to use "select *", as then you have no idea what
// fields you will get back. Better to list exactly what you want.
$select = "SELECT DISTINCT * FROM registrants WHERE (paid='Y' AND course_id = '$course_id' AND course_date = '$course_date')";
// This assume the db is already open as $dbc
$result = mysqli_query($dbc, $select);
// build header row
$header = '';
$field_count = mysqli_num_field($result);
for ($i = 0; $i < $field_count; $i++) {
$finfo = mysqli_fetch_field_direct($result,$i);
$name = $finfo->name;
$header .= $name . "\t";
// I'm not familiar with a mysqli_field_name function and couldn't find it in the docs.
// Whatever.
}
$data = $header . "\n";
// Then get all the rows of data
while($row = mysqli_fetch_row($result)) {
$line = '';
foreach($row as $value) {
if (!isset($value) OR $value == "") {
$value = "\t";
} else {
$value = str_replace('"', '""', $value);
$value = '"' . $value . '"' . "\t";
$line .= $value;
}
$data .= trim($line)."\n";
}
... and then whatever you need to do with this thing ...