PHP with JSON issue - php

Question

I'm new to PHP and I've encountered an issue that is driving me crazy. Perhaps someone here can let me know what I'm doing wrong.
I have a from that a user fills out. The below script is using the date entered into the mysql database to generate json data:
<?php
include("../includes.php");
$sq = new SQL();
$TableName = "permissions";
$Fields = $_POST["Fields"];
$FieldsSTR = "`" . str_replace("*;*","`,`", $Fields) . "`";
$Join = "AND";
$Start = 0;
$Limit = $_POST["Limit"];
if($Limit == "")$Limit = 1000;
$Where = $_POST["Where"];
$WhereSTR = "";
if($Where !== "")$WhereSTR = str_replace("*;*"," $Join ", $Where);
$q = "SELECT $FieldsSTR FROM `$TableName` $WhereSTR";
$data = $sq->sqlQuery($q);
if(sizeof($data)>0)array_shift($data);
header("Content-Type: application/json");
echo "[";
foreach($data as $k=>$line){
echo "[";
echo "\"" . str_replace("*;*","\",\"",$line) . "\"";
echo "]";
if($k < sizeof($data) - 1)echo ",";
}
echo "]";
exit;
?>
The problem that I'm having is that it has stopped working. One day it's fine and the next day it's not working. I'm thinking that maybe the cause of this problem is that crazy user data has been entered into the database. In my foreach statement I tried to replace the ";" with a "" tag, but that didn't work.
Has anyone encountered this issue before? Perhaps someone can point me in the right direction!
Thanks
Jason

Answer 1

Thanks everyone for your input. I was able to stumble on an fix to my immediate problem. I changed my foreach loop to the following:
foreach($data as $k=>$line){
$parts = explode("*;*",$line);
$NEWLINE = array();
for($i = 0;$i < sizeof($parts);$i++){
$value = $parts[$i];
$value = str_replace("\r","<br>",str_replace("\n","<br>",$value));
$NEWLINE[] = "\"" . $value . "\"";
}
$FINDATA[] = "[" . implode(",",$NEWLINE) . "]";
}
But I will now look into into using json_encode() as mentioned in the comments.
Thanks,
Jason