在PHP MySQL SELECT中嵌套if語句

Question

我需要交叉引用行。 如果該行不存在，則將其插入。

在將其插入數據庫之前，需要遵循以下條件：

首先找到屬於該用戶的約會（ user_id ）。

然后找到與約會ID（ appointment_id ID）匹配的約會。 如果約會ID不存在，請繼續執行下一步。

如果約會ID不存在，則搜索約會是否與約會日期和時間（ appointment_date日期）（ appointment_time時間）相匹配。

如果不存在，則將其INSERT數據庫。

到目前為止，這是我的代碼。 如何使SELECT嵌套if語句更快，更簡單？

// Search for appointment by appointment ID to see if it already exists
$stmt = $dbh->prepare("SELECT id FROM users WHERE user_id = :user_id AND appointment_id = :appointment_id LIMIT 1");
$stmt->bindParam(':user_id', $userId);
$stmt->bindParam(':appointment_id', $appointmentId);
$stmt->execute();
$result = $stmt->fetch(PDO::FETCH_ASSOC);

// If appointment does not already exist, search for appointment by date and time
if(!$result) {
    $stmt = $dbh->prepare("SELECT id FROM users WHERE user_id = :user_id AND appointment_date = :appointment_date AND appointment_time = :appointment_time LIMIT 1");
    $stmt->bindParam(':user_id', $userId);
    $stmt->bindParam(':appointment_date', $appointmentDate);
    $stmt->bindParam(':appointment_time', $appointmentTime);
    $stmt->execute();
    $result2 = $stmt->fetch(PDO::FETCH_ASSOC);

    if(!$result2) {
        // If appointment does not already exist, insert into database:
        $stmt = $dbh->prepare("INSERT INTO...")
    }
}

我怎樣才能使它更快，更簡單/更短？

Answer 1

如果您不需要區分兩個查詢，則只需組合您的條件即可：

SELECT id FROM users WHERE user_id = :user_id AND 
 (appointment_id = :appointment_id OR 
  appointment_date = :appointment_date AND appointment_time = :appointment_time)
LIMIT 1

Answer 2

我認為您可以嘗試使用UNION僅具有一個查詢和一半的代碼。

// Search for appointment by appointment ID to see if it already exists
$stmt = $dbh->prepare("(SELECT id FROM users WHERE user_id = :user_id AND appointment_id = :appointment_id) UNION (SELECT id FROM users WHERE user_id = :user_id AND appointment_date = :appointment_date AND appointment_time = :appointment_time) LIMIT 1");
$stmt->bindParam(':user_id', $userId);
$stmt->bindParam(':appointment_id', $appointmentId);
$stmt->bindParam(':appointment_date', $appointmentDate);
$stmt->bindParam(':appointment_time', $appointmentTime);
$stmt->execute();
$result = $stmt->fetch(PDO::FETCH_ASSOC);

// If appointment does not already exist, search for appointment by date and time
if(!$result) {
    $stmt = $dbh->prepare("INSERT INTO...")
}

我沒有在上面真正測試過此代碼。 它可能需要一些調整。

告訴我是否有什么問題。