JSON formatting errors for two files - php

Question

I would like to know, I have just created my datatables, but two of them are giving JSON formatting errors. I am doing a join of two tables in these two. I tried running the query in phpmyadmin, and it works just fine Here is one example of my server-side files:
<?php
$username="drup197";
$password="*****";
$database="census";
$server="localhost";
$link = mysqli_connect($server,$username,$password,$database);
//#mysql_select_db($database,$link) or die( "Unable to select database");
$query = "
SELECT *
FROM national_age_gender_demographics INNER JOIN arizona_age_gender_demogrpahics
WHERE national_age_gender_demographics.age_group = arizona_age_gender_demogrpahics.age_group
ORDER BY national_age_gender_demographics.index_number";
$result = mysqli_query($link,$query);
if(!$result) die( "Query: " . $query . "\nError:" . mysql_error() );
//print_r($row);
$tableData = '{"aaData": [[';
$numRows = $result->num_rows;
$row = mysqli_fetch_array($result);
for ($i = 0; $i < $numRows; $i++) {
if ($i != 0) {
$tableData .= ",[";
}
$tableData .= '"' . $row['age_group'] . '",';
$tableData .= '"' . $row['national_age_gender_demographics.both_pop'] . '",';
$tableData .= '"' . $row['national_age_gender_demographics.male_pop'] . '",';
$tableData .= '"' . $row['national_age_gender_demographics.female_pop'] . '",';
$tableData .= '"' . $row['national_age_gender_demographics.male_percent'] . '",';
$tableData .= '"' . $row['national_age_gender_demographics.female_percent'] . '",';
$tableData .= '"' . $row['national_age_gender_demographics.both_percent'] . '",';
$tableData .= '"' . $row['national_age_gender_demographics.males_per_100_females'] . '",';
$tableData .= '"' . $row['arizona_age_gender_demographics.both_pop'] . '",';
$tableData .= '"' . $row['arizona_age_gender_demographics.male_pop'] . '",';
$tableData .= '"' . $row['arizona_age_gender_demographics.female_pop'] . '",';
$tableData .= '"' . $row['arizona_age_gender_demographics.male_percent'] . '",';
$tableData .= '"' . $row['arizona_age_gender_demographics.female_percent'] . '",';
$tableData .= '"' . $row['arizona_age_gender_demographics.both_percent'] . '",';
$tableData .= '"' . $row['arizona_age_gender_demographics.males_per_100_females'] . '"]';
if ($i != $numRows - 1) {
$row = mysqli_fetch_array($result);
}
}
$tableData .= ']}';
echo $tableData;
?>
Does anyone know what is wrong here?

Answer 1

Firstly Steven is right, its better to use the json encode (or at least neater) to create your json, save you from the messy ifs and bracket business.
I would also recommend using mysqli_fetch_assoc rather than using mysqli_fetch_array, which as you currently specified should return both associative and numbered results (see here http://php.net/manual/en/mysqli-result.fetch-array.php), which probably messes up your results.
eg:
...
$row = mysqli_fetch_assoc($result);
$json_data = json_encode($row);
echo $json_data;
?>
Try that and see how you get on?