php - 无法使用 MySQLi_connect 连接到 MySQL

Question

我正在尝试使用 ajax、php 和 MySql 获取结果。但是，我的服务器端脚本出现以下错误。

Warning: mysqli_select_db() expects parameter 1 to be mysqli, resource given in D:\htdocs\classes\xxx on line 10

Warning: mysql_query(): supplied argument is not a valid MySQL-Link resource

服务端代码如下:

<?php
$q = intval($_GET['q']);

$con= mysqli_connect("localhost","root","abcd123") or die ("could not connect to mysql"); 

mysqli_select_db($con,"payrolldb001") or die ("no database"); 

$sql="SELECT substationid,substationcode FROM wms_substation WHERE assemblylineid = '".$q."'";

$result = mysqli_query($con,$sql);


echo "<select>";
while($row = mysqli_fetch_array($result))
  {
  echo "here";
  echo "<option>". $row['substationcode'] . "</option>";
  }
echo "</select>";

mysqli_close($con);
?>

我不知道我哪里出错了。请帮忙。

Answer 1

试试这个，

$con = mysqli_connect("localhost","root","abcd123","payrolldb001") or die("Error " . mysqli_error($con));
$sql="SELECT substationid,substationcode FROM wms_substation WHERE assemblylineid = '".$q."'";

$result = mysqli_query($con,$sql);
...

或者

$con= mysqli_connect("localhost","root","abcd123") or die ("could not connect to mysql"); 

mysqli_select_db($con,"payrolldb001") or die ("no database"); 

阅读mysqli_select_db