89

我想要做的是INSERT我的数据库中的订阅者，但IF EXISTS它应该UPDATE是一行，ELSE INSERT INTO一个新行。

当然，我首先连接到数据库，然后GET从url 字符串连接到数据库。$name$email$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'];

这有效，但只是添加了新行；

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

mysqli_close($con);

这是我尝试过的；

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);

但是它们都不起作用，我做错了什么？

任何帮助是极大的赞赏！

4

2 回答 2

220

  1. 如果不存在，请在您的列上创建一个UNIQUE约束：subs_email

    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)

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

  1. 请注意，我使用参数占位符代替了字符串文字，因为确实应该使用参数化语句来防御 SQL 注入攻击。
于 2013-03-13T11:26:37.450 回答
2

试试这个：

INSERT INTO `center_course_fee` (`fk_course_id`,`fk_center_code`,`course_fee`) VALUES ('69', '4920153', '6000') ON DUPLICATE KEY UPDATE `course_fee` = '6000';
于 2020-10-16T04:34:04.457 回答