php - Using curl to load data from webservice bt getting error

one text

$ch = curl_init();
 curl_setopt($ch, CURLOPT_URL,"webservcieLink");
 curl_setopt($ch, CURLOPT_POST, 1);
 curl_setopt($ch, CURLOPT_POSTFIELDS, "select * from table_name");
 curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
 $server_output = curl_exec($ch);
 $xml = new SimpleXMLElement($server_output);
 $xml = json_decode($xml, true);
curl_close ($ch);

Error I am getting is : Warning: SimpleXMLElement::__construct(): Entity: line 28: parser error : AttValue: " or ' expected

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