如何使用mysqli判断列是否为主键? [英] how to tell if column is primary key using mysqli?

问题描述

我正在将我的一些代码从旧的mysql扩展转换为PHP中的mysqli扩展.以前，通过mysql扩展，我使用了一些类似这样的代码来在表中查找主键:

I am converting some of my code from the older mysql extension to the mysqli extension in PHP. Previously, with the mysql extension, I had used some code like this to find the primary key in a table:

while ($i < mysql_num_fields($result)) {
    $meta = mysql_fetch_field($result, $i);
    if ($meta->primary_key == 1){ 
        $primary_key = $meta->name; 
    }
    $i++;
}

$meta->primary_key == 1非常方便.

到目前为止，我已经转换为使用mysqli的代码:

So far I have converted to code to using mysqli:

while ($i < $result->field_count) {
    $meta = $result->fetch_field;
    if ($meta->primary_key == 1){ 
        $primary_key = $meta->name; 
    }
    $i++;
}

当然，通过查看文档此处，我们可以看到$meta->primary_key在mysqli中不存在.我看到有一个$meta->flags.这是我的最佳猜测，尽管我不确定拥有主键时flags的值是多少.

Of course, from looking at the docs here we can see that $meta->primary_key doesn't exist in mysqli. I see that there is a $meta->flags. This is my best guess, although i am not sure of what value flags should be when I have a primary key.

有人知道我如何使用mysqli判断哪一列是表的主键吗?

Does anyone know how I tell which column is the primary key for a table using mysqli?

谢谢！

编辑 这是一些工作代码:

EDIT Here is some working code:

//get primary key
$primary_key = '';
while ($meta = $result->fetch_field()) {
    if ($meta->flags & MYSQLI_PRI_KEY_FLAG) { 
        $primary_key = $meta->name; 
    }
}

推荐答案

您非常接近，您将需要flags属性.

You were very close, you will need the flags property.

您要查找的标志是 MYSQLI_PRI_KEY_FLAG ，表示:

The flag you are looking for is MYSQLI_PRI_KEY_FLAG, which means:

字段是主索引的一部分

Field is part of a primary index

您可以使用以下方法测试此标志:

You can test for this flag with something like:

if ($meta->flags & MYSQLI_PRI_KEY_FLAG) { 
  //it is a primary key!
}

您在此处将&用作按位AND运算符.

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