PHP检查MySQL中是否存在值[关闭]

Question

我试图复制 How to Check if value exists in a MySQL database 并自己制作，但由于某种原因它不起作用......

这是我得到的：

<?php
$host = '127.0.0.1';
$username = 'root';
$password = '';
$dbname = 'multiplayer';
$con=mysqli_connect($host, $username, $password, $dbname);

$check_player_ip=mysqli_query($con, 'SELECT `player_ip` FROM `playerdata` WHERE username = "remco" AND active = 0');
    if (mysqli_num_rows($check_player_ip) == 0) {
      //didnt find anything
    } else{
      //found something
    }
?>

我收到此错误： 解析错误：语法错误，第 1 行 C:\xampp\htdocs\test.php 中出现意外的 '$check_player_ip' (T_VARIABLE)

解决方案

如果您收到 T_VARIABLE 错误，请检查此规则之前的变量。您可能忘记了“;”的位置xD

感谢大家的支持！

Answer 1

试试这个：

<?php 
$host = '127.0.0.1';
$username = 'root';
$password = '';
$dbname = 'multiplayer';

$con = new mysqli( $host, $username, $password, $dbname );

/* Check Connection */
    if ( $con->connect_error ) {
        printf( "Connect failed: %s\n", $con->connect_error );
        exit();
    }

/* Query - Returns a resultset */
    if ( $result = $con->query('SELECT `player_ip` FROM `playerdata` WHERE username = "remco" AND active = 0 ') ) {

    if ( $result->num_rows <= 0 ) {
      //didnt find anything
          printf("No player");
    } else {
      //found something
          printf("Select returned %d rows.\n", $result->num_rows);
    }

    /* free result set */
        $result->close();
}

/* close connection */
    $con->close();
?>

Answer 2

您正在混合 MySQL API，它们不会混合在一起。 mysql_num_rows

使用mysqli_num_rows()

还要确保您的数据库连接也是mysqli_* 而不是mysql_*

EDIT在您编辑了您的问题之后。

您需要将数据库连接传递给您的查询：

$check_player_ip=mysqli_query($con,'SELECT...`

$con 是您的数据库连接。相应地改变。

加上WHERE username = remco - 单词remco 需要用引号括起来，它是一个字符串而不是int。

WHERE username = 'remco'

---

旁注：

您当前的代码对SQL injection开放。
使用prepared statements，或PDO with prepared statements。

---

编辑 2：

尝试颠倒引号：

$check_player_ip=mysqli_query($con, "SELECT `player_ip` FROM `playerdata` WHERE username = 'remco' AND active = 0");
    if (mysqli_num_rows($check_player_ip) == 0) {
      //didnt find anything
    } 

Answer 3

你应该执行那个 mysqli 查询...

while($rows = mysql_arrayAssoc($ursql)){
    $data[]=$rows;
}
if($something== $data['attribute']) //attribute(id,name...)
    echo "ok some data is in"
else 
   echo "no matching data"

希望对你有帮助:)