php 检查 mysqli_query 是否没有值？
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Checking if mysqli_query has no values?
提问by Peter Jewicz
I have the following code for a sign up form. I want to check the email to see if it's already logged in the database, and if so return an error.
我有以下用于注册表单的代码。我想检查电子邮件以查看它是否已登录到数据库中，如果已登录，则返回错误。
$name = $_POST['name'];
$email = $_POST['email'];
$result = mysqli_query($connection,"SELECT * FROM users WHERE email='$email'");
if($result=="")
{
echo("email was not found");
}
else
{
echo("email was found");
}
I'm having trouble if the results come back as empty. I've tried using several things and can't figure out how to get it work correctly if nothing is found.
如果结果返回为空，我就会遇到麻烦。我尝试过使用几种方法，但如果找不到任何东西，就无法弄清楚如何使其正常工作。
回答by Ananth
Use mysqli_num_rowsto check if any rows were returned or not.
使用mysqli_num_rows检查是否有任何行返回。
回答by Shankar Akunuri
use mysqli_num_rowslike this
mysqli_num_rows像这样使用
if (mysqli_num_rows($result) == 0) {
echo "email was not found";
} else {
echo "email was found";
}
回答by eric_zyh
if(empty($result))
{
echo("email was not found");
}
