用 mysqli_result::fetch_column 提取数据并与外部 API 结合处理

gitbox 2025-08-22
<span><span><span class="hljs-meta">&lt;?php</span></span><span>
</span><span><span class="hljs-comment">// 这是与文章内容无关的PHP代码示例，演示数据库连接和简单查询</span></span><span>
</span><span><span class="hljs-variable">$mysqli</span></span><span> = </span><span><span class="hljs-keyword">new</span></span><span> </span><span><span class="hljs-title function_ invoke__">mysqli</span></span><span>(</span><span><span class="hljs-string">"localhost"</span></span><span>, </span><span><span class="hljs-string">"user"</span></span><span>, </span><span><span class="hljs-string">"password"</span></span><span>, </span><span><span class="hljs-string">"database"</span></span><span>);
</span><span><span class="hljs-keyword">if</span></span><span> (</span><span><span class="hljs-variable">$mysqli</span></span><span>-&gt;connect_errno) {
    </span><span><span class="hljs-keyword">die</span></span><span>(</span><span><span class="hljs-string">"连接失败: "</span></span><span> . </span><span><span class="hljs-variable">$mysqli</span></span><span>-&gt;connect_error);
}
</span><span><span class="hljs-variable">$query</span></span><span> = </span><span><span class="hljs-string">"SELECT id, name FROM users LIMIT 5"</span></span><span>;
</span><span><span class="hljs-variable">$result</span></span><span> = </span><span><span class="hljs-variable">$mysqli</span></span><span>-&gt;</span><span><span class="hljs-title function_ invoke__">query</span></span><span>(</span><span><span class="hljs-variable">$query</span></span><span>);
</span><span><span class="hljs-meta">?&gt;</span></span><span>

&lt;hr&gt;

</span><span><span class="hljs-meta">&lt;?php</span></span><span>
<span class="hljs-comment">/*
 * 用 mysqli_result::fetch_column 提取数据并与外部 API 结合处理
 *
 * 在PHP中，mysqli扩展是操作MySQL数据库的常用方法之一。
 * 从PHP 8.1起，mysqli_result类新增了fetch_column方法，
 * 可以直接提取查询结果中的某一列，方便快捷。
 *
 * 本文将介绍如何使用fetch_column提取单列数据，并将提取的数据与外部API结合处理，
 * 例如调用一个模拟的API，获取每个用户的详细信息。
 */</span>

</span><span><span class="hljs-variable">$mysqli</span></span><span> = </span><span><span class="hljs-keyword">new</span></span><span> </span><span><span class="hljs-title function_ invoke__">mysqli</span></span><span>(</span><span><span class="hljs-string">"localhost"</span></span><span>, </span><span><span class="hljs-string">"user"</span></span><span>, </span><span><span class="hljs-string">"password"</span></span><span>, </span><span><span class="hljs-string">"database"</span></span><span>);
</span><span><span class="hljs-keyword">if</span></span><span> (</span><span><span class="hljs-variable">$mysqli</span></span><span>-&gt;connect_errno) {
    </span><span><span class="hljs-keyword">die</span></span><span>(</span><span><span class="hljs-string">"连接失败: "</span></span><span> . </span><span><span class="hljs-variable">$mysqli</span></span><span>-&gt;connect_error);
}

</span><span><span class="hljs-comment">// 查询用户ID列表</span></span><span>
</span><span><span class="hljs-variable">$sql</span></span><span> = </span><span><span class="hljs-string">"SELECT id FROM users"</span></span><span>;
</span><span><span class="hljs-variable">$result</span></span><span> = </span><span><span class="hljs-variable">$mysqli</span></span><span>-&gt;</span><span><span class="hljs-title function_ invoke__">query</span></span><span>(</span><span><span class="hljs-variable">$sql</span></span><span>);

</span><span><span class="hljs-keyword">if</span></span><span> (!</span><span><span class="hljs-variable">$result</span></span><span>) {
    </span><span><span class="hljs-keyword">die</span></span><span>(</span><span><span class="hljs-string">"查询失败: "</span></span><span> . </span><span><span class="hljs-variable">$mysqli</span></span><span>-&gt;error);
}

</span><span><span class="hljs-comment">// 使用fetch_column提取所有用户ID，返回数组</span></span><span>
</span><span><span class="hljs-variable">$user_ids</span></span><span> = [];
</span><span><span class="hljs-keyword">while</span></span><span> (</span><span><span class="hljs-variable">$id</span></span><span> = </span><span><span class="hljs-variable">$result</span></span><span>-&gt;</span><span><span class="hljs-title function_ invoke__">fetch_column</span></span><span>(</span><span><span class="hljs-number">0</span></span><span>)) {  </span><span><span class="hljs-comment">// 参数0表示取第一列</span></span><span>
    </span><span><span class="hljs-variable">$user_ids</span></span><span>[] = </span><span><span class="hljs-variable">$id</span></span><span>;
}

</span><span><span class="hljs-comment">// 关闭查询结果集</span></span><span>
</span><span><span class="hljs-variable">$result</span></span><span>-&gt;</span><span><span class="hljs-title function_ invoke__">free</span></span><span>();

</span><span><span class="hljs-comment">// 模拟调用外部API，根据用户ID批量获取用户信息</span></span><span>
</span><span><span class="hljs-comment">// 这里我们用一个简单函数代替真实API调用</span></span><span>
</span><span><span class="hljs-function"><span class="hljs-keyword">function</span></span></span><span> </span><span><span class="hljs-title">getUserInfoFromApi</span></span><span>(</span><span><span class="hljs-params"><span class="hljs-keyword">array</span></span></span><span> </span><span><span class="hljs-variable">$ids</span></span><span>): </span><span><span class="hljs-title">array</span></span><span> {
    </span><span><span class="hljs-variable">$data</span></span><span> = [];
    </span><span><span class="hljs-keyword">foreach</span></span><span> (</span><span><span class="hljs-variable">$ids</span></span><span> </span><span><span class="hljs-keyword">as</span></span><span> </span><span><span class="hljs-variable">$id</span></span><span>) {
        </span><span><span class="hljs-comment">// 模拟API返回数据结构</span></span><span>
        </span><span><span class="hljs-variable">$data</span></span><span>[</span><span><span class="hljs-variable">$id</span></span><span>] = [
            </span><span><span class="hljs-string">'id'</span></span><span> =&gt; </span><span><span class="hljs-variable">$id</span></span><span>,
            </span><span><span class="hljs-string">'name'</span></span><span> =&gt; </span><span><span class="hljs-string">"User_<span class="hljs-subst">$id</span></span></span><span>",
            </span><span><span class="hljs-string">'email'</span></span><span> =&gt; </span><span><span class="hljs-string">"user<span class="hljs-subst">{$id}</span></span></span><span>@example.com",
        ];
    }
    </span><span><span class="hljs-keyword">return</span></span><span> </span><span><span class="hljs-variable">$data</span></span><span>;
}

</span><span><span class="hljs-comment">// 调用API获取详细信息</span></span><span>
</span><span><span class="hljs-variable">$user_details</span></span><span> = </span><span><span class="hljs-title function_ invoke__">getUserInfoFromApi</span></span><span>(</span><span><span class="hljs-variable">$user_ids</span></span><span>);

</span><span><span class="hljs-comment">// 处理并输出结果</span></span><span>
</span><span><span class="hljs-keyword">foreach</span></span><span> (</span><span><span class="hljs-variable">$user_details</span></span><span> </span><span><span class="hljs-keyword">as</span></span><span> </span><span><span class="hljs-variable">$user</span></span><span>) {
    </span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"用户ID: <span class="hljs-subst">{$user['id']}</span></span></span><span>&lt;br&gt;";
    </span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"姓名: <span class="hljs-subst">{$user['name']}</span></span></span><span>&lt;br&gt;";
    </span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"邮箱: <span class="hljs-subst">{$user['email']}</span></span></span><span>&lt;br&gt;&lt;hr&gt;";
}

</span><span><span class="hljs-variable">$mysqli</span></span><span>-&gt;</span><span><span class="hljs-title function_ invoke__">close</span></span><span>();
</span><span><span class="hljs-meta">?&gt;</span></span><span>
</span></span>
相关标签:
mysqli_result API
mysqli_result::fetch_column