如何在可为空的列中插入实际的NULL值? [英] How to insert an actual NULL value into a nullable column?

问题描述

function save($gmt, $name, $address, $phone, $remark)
{
    $query= "INSERT INTO `user` (`gmt`, `name`, `address`, `phone`, `remark`) VALUES ('$gmt', '$name', '$address', '$phone', '$remark')";
    mysql_query($query);
}

此处，地址，电话和备注可以为NULL.每当变量设置为NULL并且列为空时，我都需要保存NULL，而不是插入空字符串.

Here, address, phone, and remark can be NULL. I need it to save NULL whenever the variable is set to NULL and the column is nullable, instead of inserting an empty string.

如何使用PHP将NULL值插入数据库?

How can I insert NULL value into the database using PHP?

推荐答案

这是PHP解决方案，但是由于不建议使用mysql，因此必须使用mysqli，请阅读有关 SQL注入

This is PHP solution, but you have to use mysqli because mysql deprecated, please read more about mysqli. Also, you must consider SQL injection

function save($gmt, $name, $address, $phone, $remark)
{
  if(empty($phone)){
   $phone = 'NULL';
  }else{
   $phone = "'".$phone."'";
  }
  if(empty($remark)){
   $remark = 'NULL';
  }else{
   $remark = "'".$remark."'";
  }
    $query= "INSERT INTO `user` (`gmt`, `name`, `address`, `phone`, `remark`) VALUES ('$gmt', '$name', '$address', $phone, $remark)";
    mysql_query($query);
}
//tests
save("a", "b", "c", "", "")."<br>";
save("a", "b", "c", "d", "")."<br>";
save("a", "b", "c", "d", "e")."<br>";
/*
INSERT INTO `user` (`gmt`, `name`, `address`, `phone`, `remark`) VALUES ('a', 'b', 'c', NULL, NULL)
INSERT INTO `user` (`gmt`, `name`, `address`, `phone`, `remark`) VALUES ('a', 'b', 'c', 'd', NULL)
INSERT INTO `user` (`gmt`, `name`, `address`, `phone`, `remark`) VALUES ('a', 'b', 'c', 'd', 'e')
*/
?>

演示

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