[英]mysqli_query returns false with error code 0, but query succeeds
[英]Mysqli_query returns false and Mysqli_error returns NULL?
我一直在創建預訂系統並創建約會,但是我的SQL語句不起作用。 我一直在尋找解決方案,但無濟於事。
下面列出的是我的PHP代碼。 我的第一個SQL語句可以正常工作並返回正確的ClientID,但是,第二個SQL語句並未將其全部插入數據庫中。 我對結果做了var_dumps,返回bool(false),對結果做了mysqli_error,返回null。 我的錯誤消息最后僅顯示echo'd消息,也沒有mysqli_error或錯誤號。
(注意:為了保護數據,某些值已更改/刪除)
<?php
session_start();
if(! $_SESSION['Username']) {
header("location:Index.php");
}
$servername = "localhost";
$username = "root";
$password = "";
$dbname = "";
$tablename = "appointmentinformation";
$tablenamed = "clientinformation";
$connection = mysqli_connect("$servername", "$username", "$password", "$dbname") or die("Could not connect to the database");
$clientusername = $_SESSION['Username'];
$sql = "SELECT ClientID FROM $tablenamed WHERE Username = '$clientusername' LIMIT 1";
$results = mysqli_query($connection, $sql);
if (! $results) {
echo ("Could not select the data : " . mysql_error());
} else {
$datarows = mysqli_fetch_row($results);
$clientid = $datarows[0];
}
$date = $_POST["Date"];
$month = $_POST["Month"];
$year = $_POST["Year"];
$time = $_POST["Time"];
$length = $_POST["Length"];
$date = stripslashes($date);
$month = stripslashes($month);
$year = stripslashes($year);
$time = stripslashes($time);
$length = stripslashes($length);
$date = mysqli_real_escape_string($date);
$month = mysqli_real_escape_string($month);
$year = mysqli_real_escape_string($year);
$time = mysqli_real_escape_string($time);
$length = mysqli_real_escape_string($length);
$query = "INSERT INTO appointmentinformation (ClientID, Length, Date, Month, Year, Time, Price) VALUES ('$clientid', '$length', '$date', '$month', '$year', '$time', '$price')";
$result = mysqli_query($connection, $query);
if ($result) {
header("Location:UserCP.php");
} else {
echo ("Could not insert data : " . mysqli_error($result) . " " . mysqli_errno());
}
?>
$query = "INSERT INTO appointmentinformation (ClientID, Length, Date, Month, Year, Time, Price) VALUES ('$clientid', '$length', '$date', '$month', '$year', '$time', '$price')";
$result = mysqli_query($connection, $query);
if ($result) {
header("Location:UserCP.php");
} else {
echo ("Could not insert data : " . mysqli_error($result) . " " . mysqli_errno());
}
mysqli_query返回的結果為空。 這會將您發送到代碼的else分支。 然后,您編碼了mysqli_error($ result)等於mysqli_error(null)。
我讀過的文檔說要使用與查詢的“鏈接”初始化變量。 您這樣做的原因是:
$connection = mysqli_connect("$servername", "$username", "$password", "$dbname") or die("Could not connect to the database");
現在,您要將其編碼為mysqli_error($ connection)和mysqli_errno($ connection)。
另一個建議。 在mysqli_connect語句之后立即添加此代碼。
if (mysqli_connect_errno())
{
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}
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