SQL – IF EXISTS UPDATE ELSE INSERT INTO

我想要做的是INSERT订阅服务器在我的数据库，但IF EXISTS它应该UPDATE行， ELSE INSERT INTO一个新的行。

当然，我先连接到数据库，并从urlstring中GET $name ， $email和$birthday 。

 $con=mysqli_connect("localhost","---","---","---"); // Check connection if (mysqli_connect_errno()) { echo "Failed to connect to MySQL: " . mysqli_connect_error(); } $name=$_GET['name']; $email=$_GET['email']; $birthday=$_GET['birthday']; 

这工作，但只是增加了新的一行;

 mysqli_query($con,"INSERT INTO subs (subs_name, subs_email, subs_birthday) VALUES ('$name', '$email', '$birthday')"); mysqli_close($con); 

这是我的尝试;

 mysqli_query($con,"INSERT INTO subs (subs_name, subs_email, subs_birthday) VALUES '$name', '$email', '$birthday' ON DUPLICATE KEY UPDATE subs_name = VALUES($name), subs_birthday = VALUES($birthday)"); mysqli_close($con); 

和

 mysqli_query($con,"IF EXISTS (SELECT * FROM subs WHERE subs_email='$email') UPDATE subs SET subs_name='$name', subs_birthday='$birthday' WHERE subs_email='$email' ELSE INSERT INTO subs (subs_name, subs_email, subs_birthday) VALUES ('$name', '$email', '$birthday')"); mysqli_close($con); 

和

 mysqli_query($con,"IF NOT EXISTS(SELECT * FROM subs WHERE subs_email='$email') Begin INSERT INTO subs (subs_name, subs_email, subs_birthday) VALUES ('$name', '$email', '$birthday') End"); mysqli_close($con); 

但是他们都没有工作，我做错了什么？

任何帮助是极大的赞赏！

Answer 1

1. 在您的subs_email列上创build一个UNIQUE约束 （如果尚不存在）：

    ALTER TABLE subs ADD UNIQUE (subs_email) 

2. 使用INSERT ... ON DUPLICATE KEY UPDATE ：

    INSERT INTO subs (subs_name, subs_email, subs_birthday) VALUES (?, ?, ?) ON DUPLICATE KEY UPDATE subs_name = VALUES(subs_name), subs_birthday = VALUES(subs_birthday) 

您可以使用UPDATE子句中的VALUES（col_name）函数来引用来自INSERT的INSERT部分的列值… ON DUPLICATE KEY UPDATE – dev.mysql.com

3. 请注意，我已经在string文字的地方使用了参数占位符，因为实际上应该使用参数化语句来抵御SQL注入攻击 。