php - 如何将功能从使用 mysql 更改为 mysqli

Question

我正在为我的 cms 切换到 mysqli，并且在将查询和获取功能切换到 mysqli 时遇到一些问题，我不断收到这样的错误

Warning: mysqli_query() expects parameter 1 to be mysqli, null given in /home/u250000297/public_html/forum/system/db.php on line 48 Warning: mysqli_fetch_array() expects parameter 1 to be mysqli_result, null given in /home/u250000297/public_html/forum/system/db.php on line 49 Warning: mysqli_query() expects parameter 1 to be mysqli, null given in /home/u250000297/public_html/forum/system/db.php on line 48 Warning: mysqli_fetch_array() expects parameter 1 to be mysqli_result, null given in /home/u250000297/public_html/forum/system/db.php on line 49  Warning: mysqli_real_query() expects parameter 1 to be mysqli, null given in /home/u250000297/public_html/forum/system/db.php on line 41 Warning: mysqli_error() expects parameter 1 to be mysqli, null given in /home/u250000297/public_html/forum/system/db.php on line 41

我尝试过不同的要求，如下所示:

function query($query) {
    $sql = mysqli_real_query($connection, $query) or die (mysqli_error($connection));
    return $sql;
    mysqli_free_result($sql);

}

function fetch($query) {
    $data = mysqli_query($connection, $query);
    mysqli_fetch_array($data);
    return($data);
}

2:
function query($query) {
    $sql = mysqli_query($this->db, $query) or die(mysqli_error());
    return $sql;
    mysqli_free_result($sql);

}

function fetch($query) {
    $data = mysqli_query($this->db, $query);
    mysqli_fetch_array($data);
    return($data);
}

我一直遇到同样的错误，我不知道我是否做错了什么。你能帮助我并给我一些提示吗？，我在尝试使用 mysqli 之前的原始代码

function query($query) {
    $sql = mysql_query($query, $this->db) or die(mysql_error());
    return $sql;
    mysql_free_result($sql);
}



function fetch($query) {
    $sql = mysql_fetch_array(mysql_query($query, $this->db));
    return $sql;
    mysql_free_result($sql);

}

Answer 1

首先建立连接和数据库名称

$this->con = mysqli_connect($this->host,$this->user,$this->pass);
mysqli_select_db( $this->con,$this->db );

然后像这样执行查询

function query_execute( $query )
{
    $this->query = mysqli_query( $this->con,$query );
    if ($this->query->num_rows > 0 ) {
        return $this->query;
    } else {
        return mysqli_error( $this->con );
    }
}