PHP MySQL查询中调用问题

Question

PHP MySQL查询中调用问题

3

我正在尝试从PHP中进行查询调用，但我不确定为什么它无法正常工作。看起来我在查询中的操作有问题。在添加where子句和bindParam之前，一切都正常工作。代码执行正确，但在进行查询和绑定后停止。请问是否有人能看到我是否做对了？可能与对gender的post调用有关，我无法输出$gender。感谢任何见解！

 <!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Practice Work 5</title>
</head>
<body>

<form action="babynames.php" method = "post">
    Year:<br>
    <input type="text" name="year">
    <input type="submit" value="Submit">
</form>

<select name = "gender">
    <option value="male">Male</option>
    <option value="female">Female</option>
</select>


</body>
</html>

<?php>
    $servername = "localhost";
$username = "root";
$password = "root";
$dbname = "baby";

$year = $_POST['year'];
$gender = $_POST['gender'];

// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

$sql = "SELECT Year, Name, Ranking, Gender FROM BabyNames where Year = ? and Gender = ?";
$sql -> bindParam (1, $year, PDO::PARAM_INT);
$sql -> bindParam (2, $gender, PDO::PARAM_STR);

$result = $conn->query($sql);

if ($result->num_rows > 0) {
    // output data of each row
    while($row = $result->fetch_assoc()) {
        echo "<br> Year: ". $row["Year"]. " ; Name: ". $row["Name"]. " ; Ranking: " . $row["Ranking"] . " ; Gender: " . $row["Gender"]. " ". "<br>";
    }
} else {
    echo "0 results";
}

$conn->close();
?>

- Defcon

在MySQL中进行比较时使用=而不是==。 - John Conde

2个回答

1

将此更改

$sql = "SELECT Year, Name, Ranking, Gender FROM BabyNames where Year == ? and Gender == ?";

到

$sql = "SELECT Year, Name, Ranking, Gender FROM BabyNames WHERE Year = ? AND Gender = ?";

- Edmhar

好的，谢谢！我仍然遇到问题。还有其他问题吗？也许是我绑定的方式有问题？ - Defcon

1

这并没有帮助，因为MySQL语法不区分大小写。此外，OP试图将字符串用作对象，这毫无意义。 - bksi

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- bksi · Accepted Answer

你的变量 $sql 是字符串，不是一个对象。根据http://php.net/manual/zh/mysqli-stmt.bind-param.php 在绑定参数之前，你需要先准备语句：

if ($stmt = $conn->prepare($sql)) {

    $stmt->bind_param("is", $year, $gender);
    $stmt->execute();

    $result = $stmt->get_result();
    $processedRows = 0;
    while ($row = $result->fetch_assoc()) {
        $processedRows++;
        echo "<br> Year: ". $row["Year"]. " ; Name: ". $row["Name"]. " ; Ranking: " . $row["Ranking"] . " ; Gender: " . $row["Gender"]. " ". "<br>";
    }
    if (empty($processedRows)) {  echo "0 results";  }

}
$conn->close();