使用mysqli::get_warnings 卻沒有任何警告顯示？該如何排查問題？

gitbox 2025-08-21

<span><span><span class="hljs-meta"><?php</span></span><span>
</span><span><span class="hljs-comment">// 這裡是與文章內容無關的前置代碼或聲明部分，可以根據需要自由修改</span></span><span>
</span><span><span class="hljs-title function_ invoke__">error_reporting</span></span><span>(E_ALL);
</span><span><span class="hljs-title function_ invoke__">ini_set</span></span><span>(</span><span><span class="hljs-string">'display_errors'</span></span><span>, </span><span><span class="hljs-number">1</span></span><span>);
</span><span><span class="hljs-meta">?></span></span><span>

<hr>

<h2>使用 <code>mysqli::</span><span><span class="hljs-variable constant_">get_warnings</span></span><span>

執行後，調用get_warnings()查看是否有警告。

2 . 檢查調用get_warnings()的時機
必須在執行SQL 後立即調用，且在執行下一條語句之前。否則之前的警告信息會被清空。

3 . 遍歷所有警告

有時候會有多條警告，需要循環遍歷：

 
</span><span><span class="hljs-variable">$warn</span></span><span> = </span><span><span class="hljs-variable">$mysqli</span></span><span>-></span><span><span class="hljs-title function_ invoke__">get_warnings</span></span><span>();
</span><span><span class="hljs-keyword">while</span></span><span> (</span><span><span class="hljs-variable">$warn</span></span><span>) {
    </span><span><span class="hljs-title function_ invoke__">printf</span></span><span>(</span><span><span class="hljs-string">"Warning: %s, %s, %s\n"</span></span><span>, </span><span><span class="hljs-variable">$warn</span></span><span>->errno, </span><span><span class="hljs-variable">$warn</span></span><span>->sqlstate, </span><span><span class="hljs-variable">$warn</span></span><span>->message);
    </span><span><span class="hljs-variable">$warn</span></span><span> = </span><span><span class="hljs-variable">$warn</span></span><span>-></span><span><span class="hljs-title function_ invoke__">next</span></span><span>();
}

4 . 檢查MySQL 服務器配置

確認服務器沒有關閉警告輸出，查看sql_mode中是否啟用了嚴格模式，某些模式可能導致警告被當作錯誤處理。

 <span class="fun">SHOW VARIABLES LIKE </span><span><span class="hljs-string">&#39;sql_mode&#39;</span></span><span>;</span>

5 . 確認客戶端編碼和數據類型
編碼不匹配或者字段類型不符也可能導致警告，確保數據庫和客戶端字符集一致，字段類型正確。

四、示例代碼

&lt;?php
</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>->connect_errno) {
    </span><span><span class="hljs-keyword">die</span></span><span>(</span><span><span class="hljs-string">"連接失敗: "</span></span><span> . </span><span><span class="hljs-variable">$mysqli</span></span><span>->connect_error);
}

</span><span><span class="hljs-variable">$sql</span></span><span> = </span><span><span class="hljs-string">"INSERT INTO test_table (varchar_column) VALUES ('這是一個超過字段長度限制的字符串...')"</span></span><span>;
</span><span><span class="hljs-keyword">if</span></span><span> (!</span><span><span class="hljs-variable">$mysqli</span></span><span>-></span><span><span class="hljs-title function_ invoke__">query</span></span><span>(</span><span><span class="hljs-variable">$sql</span></span><span>)) {
    </span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"執行失敗: "</span></span><span> . </span><span><span class="hljs-variable">$mysqli</span></span><span>->error;
}

</span><span><span class="hljs-variable">$warn</span></span><span> = </span><span><span class="hljs-variable">$mysqli</span></span><span>-></span><span><span class="hljs-title function_ invoke__">get_warnings</span></span><span>();
</span><span><span class="hljs-keyword">if</span></span><span> (</span><span><span class="hljs-variable">$warn</span></span><span>) {
    </span><span><span class="hljs-keyword">do</span></span><span> {
        </span><span><span class="hljs-title function_ invoke__">printf</span></span><span>(</span><span><span class="hljs-string">"警告: 編號 %d，狀態 %s，資訊 %s\n"</span></span><span>, </span><span><span class="hljs-variable">$warn</span></span><span>->errno, </span><span><span class="hljs-variable">$warn</span></span><span>->sqlstate, </span><span><span class="hljs-variable">$warn</span></span><span>->message);
    } </span><span><span class="hljs-keyword">while</span></span><span> (</span><span><span class="hljs-variable">$warn</span></span><span> = </span><span><span class="hljs-variable">$warn</span></span><span>-></span><span><span class="hljs-title function_ invoke__">next</span></span><span>());
} </span><span><span class="hljs-keyword">else</span></span><span> {
    </span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"沒有警告產生。\n"</span></span><span>;
}

</span><span><span class="hljs-variable">$mysqli</span></span><span>-></span><span><span class="hljs-title function_ invoke__">close</span></span><span>();
</span><span><span class="hljs-meta">?></span></span><span>