每次我用我的班级为 select * from table where blank=blank 调用查询时，它总是在 var_dump 上出现“NULL”，以获得班级结束时的结果。我仍然坚持这一点，不知道它为什么这样做，但它肯定没有发送任何响应，因为我什么也没得到。
mysqli.class.php
<?php
class DATABASE
{
//set up variables only for this class
private $db_host;
private $db_user;
private $db_pass;
private $db_name;
private $connection;
private $paramaters = array();
private $results = array();
private $numrows;
//call connection on call of class
public function __construct($db_host, $db_user, $db_pass, $db_name)
{
$this->host = $db_host;
$this->user = $db_user;
$this->pass = $db_pass;
$this->name = $db_name;
$this->mysqli = new mysqli($this->host, $this->user, $this->pass, $this->name) or die('There was a problem connecting to the database! Error #: '. $this->mysqli->connect_errno);
}
//close mysqli connection on class close
public function __destruct()
{
$this->mysqli->close();
}
//query
public function select($fields, $table, $where, $whereVal, $type, $orderByVal, $ASDESC, $limitVal, $sets, $setVal)
{
switch($type)
{
case "regular":
if ($where == null)
{
$queryPre = "SELECT " . $fields . " FROM " . $table;
$querySuff = "";
} else {
$queryPre = "SELECT " . $fields . " FROM " . $table;
$querySuff = " WHERE " . $where . " = ?";
}
break;
case "orderByLimit":
$queryPre = "SELECT " . $fields . " FROM " . $table;
$querySuff = " ORDER BY " . $orderByVal . " " . $ASDESC . " LIMIT " . $limitVal;
break;
case "update":
if ($where == null)
{
$queryPre = "UPDATE " . $table;
//need for loop for multiple sets, check for is_array and do multiple if so.
$querySuff = " SET " . $sets . " = " . $setVal;
} else {
$queryPre = "UPDATE " . $table;
//need for loop for multiple sets, check for is_array and do multiple if so.
$querySuff = " SET " . $sets . " = " . $setVal . " WHERE " . $where . " = ?";
}
break;
case "insert":
if ($sets == null)
{
$queryPre = "INSERT INTO " . $table;
$querySuff = " VALUES(" . setVal . ")";
} else {
$queryPre = "INSERT INTO " . $table . " (" . $sets . ")";
$querySuff = " VALUES(" . setVal . ")";
}
case "delete":
if ($where == null)
{
$queryPre = "DELETE FROM " . $table;
$querySuff = "";
} else {
$queryPre = "DELETE FROM " . $table;
$querySuff = " WHERE " . $where . " = ?";
}
}
//$sql = $queryPre . "" . $querySuff;
//var_dump($sql);
//exit;
$stmt = $this->mysqli->prepare($queryPre . "" . $querySuff) or die('There was a problem preparing the Query! Error#: '. $this->mysqli->errno);
if ($whereVal == null)
{
$stmt = $this->bindVars($stmt,$setVal);
} else {
$stmt = $this->bindVars($stmt,$whereVal);
}
$stmt->execute();
$meta = $stmt->result_metadata();
while ($field = $meta->fetch_field())
{
$parameters[] = &$row[$field->name];
}
call_user_func_array(array($stmt, 'bind_result'), $parameters);
while ($stmt->fetch())
{
$x = array();
foreach($row as $key => $val)
{
$x[$key] = $val;
}
$results[] = $x;
}
$stmt->close();
//var_dump($results);
if ($results == "" || $results == NULL)
{
return null;
} else {
return $results;
}
}
private function bindVars($stmt,$params)
{
if ($params != null)
{
$types = '';
//initial sting with types
if (is_array($params))
{
foreach($params as $param)
{
//for each element, determine type and add
if(is_int($param))
{
$types .= 'i'; //integer
} elseif (is_float($param))
{
$types .= 'd'; //double
} elseif (is_string($param))
{
$types .= 's'; //string
} else {
$types .= 'b'; //blob and unknown
}
}
} else {
if (is_int($params))
{
$types = 'i';
} elseif (is_float($params))
{
$types = 'd';
} elseif (is_string($params))
{
$types = 's';
} else {
$types = 'b';
}
}
$bind_names[] = $types;
if (is_array($params))
{
//go through incoming params and added em to array
for ($i=0; $i<count($params);$i++)
{
//give them an arbitrary name
$bind_name = 'bind' . $i;
//add the parameter to the variable variable
$$bind_name = $params[$i];
//now associate the variable as an element in an array
$bind_names[] = &$$bind_name;
}
} else {
$int0 = 0;
$bind_name = 'bind' . $int0;
$$bind_name = $params;
$bind_names[] = &$$bind_name;
}
call_user_func_array(array($stmt,'bind_param'),$bind_names);
}
return $stmt; //return the bound statement
}
}
?>
调用和检查字段的示例 - process_availability.php：
<?php
//require necessary files
require('../config/dbconfig.php');
include('../classes/mysqli.class.php');
//initiate connection
$mysqli = new DATABASE($db_host,$db_user,$db_pass,$db_name);
//take type of check
$checktype = $_POST['type'];
//check the user name
if ($checktype == "username") {
//change post to variable
$username = $_POST['username'];
//check if user name is empty
if ($username == "") {
$validuser = array("empty", "false");
echo implode(',', $validuser);
exit;
}
//if user name is more characters than 30
if (strlen($username) > 30) {
$validuser = array("max", "false");
echo implode(',', $validuser);
exit;
}
//search for same user name in database
$resultsU = $mysqli->select('*','users','username',$username,'regular',null,null,null,null,null);
//var_dump($resultsU);
if (is_array($resultsU))
{
var_dump($resultsU);
foreach($resultsU as $rowU)
{
//return results
if($rowU['username'] == "" || $rowU['username'] == NULL)
{
//user name is blank
$validuser = array("yes", "true");
echo implode(',', $validuser);
exit;
}
else {
//username is not blank, so it's taken
$validuser = array("no", "false");
echo implode(',', $validuser);
exit;
}
}
}
}
并且只是为了展示我实际上对这些信息所做的事情，这是 java 的一部分（主要只处理用户名，还有更多的电子邮件，不包括在内）： fiddle
而且，粗略地说，指向页面的链接：页面链接
我一直在这里修复其他东西，并且在技术上它有效。如果数据库中有与我输入的用户名匹配的内容，我会收到响应，但如果不匹配，由于某种原因它根本没有响应.....
具体来说......在类中倒数第二个函数的底部：
$stmt->close();
//var_dump($results);
if ($results == "" || $results == NULL)
{
return null;
} else {
return $results;
}