[Wie verwende ich MySQL_Field_len mit MySQL_Fetch_Field? Siehe Beispielerklärung]

gitbox 2025-09-23

<span><span><span class="hljs-meta">&lt;?php</span></span><span>
</span><span><span class="hljs-comment">// Dies hängt nicht mit dem Inhalt des Artikels zusammenPHPCodebeispiel</span></span><span>
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"Willkommen, um diesen Artikel zu lesen！&lt;br&gt;"</span></span><span>;
</span><span><span class="hljs-title function_ invoke__">date_default_timezone_set</span></span><span>(</span><span><span class="hljs-string">'Asia/Shanghai'</span></span><span>);
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"Aktuelle Zeit："</span></span><span> . </span><span><span class="hljs-title function_ invoke__">date</span></span><span>(</span><span><span class="hljs-string">'Y-m-d H:i:s'</span></span><span>) . </span><span><span class="hljs-string">"&lt;br&gt;"</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">/*
Artikel Titel：【mysql_field_lenÜbereinstimmenmysql_fetch_fieldWie man es zusammen benutzt？Sehen wir uns die Beispielerklärung an】
*/</span>

</span><span><span class="hljs-comment">// Im EinsatzPHParbeitenMySQLWenn die Datenbank，Viele Menschen werden auf die Notwendigkeit stoßen, die Feldlänge zu erhalten。</span></span><span>
</span><span><span class="hljs-comment">// Hier werden wir erklärenmysql_field_lenSo verwenden Sie die Funktionmysql_fetch_fieldÜbereinstimmenverwenden。</span></span><span>

</span><span><span class="hljs-comment">// 1. Stellen Sie eine Verbindung zur Datenbank her</span></span><span>
</span><span><span class="hljs-variable">$conn</span></span><span> = </span><span><span class="hljs-title function_ invoke__">mysql_connect</span></span><span>(</span><span><span class="hljs-string">'localhost'</span></span><span>, </span><span><span class="hljs-string">'root'</span></span><span>, </span><span><span class="hljs-string">'password'</span></span><span>);
</span><span><span class="hljs-keyword">if</span></span><span> (!</span><span><span class="hljs-variable">$conn</span></span><span>) {
    </span><span><span class="hljs-keyword">die</span></span><span>(</span><span><span class="hljs-string">'Die Datenbankverbindung ist fehlgeschlagen: '</span></span><span> . </span><span><span class="hljs-title function_ invoke__">mysql_error</span></span><span>());
}
</span><span><span class="hljs-title function_ invoke__">mysql_select_db</span></span><span>(</span><span><span class="hljs-string">'test_db'</span></span><span>, </span><span><span class="hljs-variable">$conn</span></span><span>);

</span><span><span class="hljs-comment">// 2. Eine Frage ausführen</span></span><span>
</span><span><span class="hljs-variable">$result</span></span><span> = </span><span><span class="hljs-title function_ invoke__">mysql_query</span></span><span>(</span><span><span class="hljs-string">'SELECT id, username, email FROM users'</span></span><span>);
</span><span><span class="hljs-keyword">if</span></span><span> (!</span><span><span class="hljs-variable">$result</span></span><span>) {
    </span><span><span class="hljs-keyword">die</span></span><span>(</span><span><span class="hljs-string">'Abfrage fehlgeschlagen: '</span></span><span> . </span><span><span class="hljs-title function_ invoke__">mysql_error</span></span><span>());
}

</span><span><span class="hljs-comment">// 3. verwendenmysql_fetch_fieldErhalten Sie Feldinformationen</span></span><span>
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"&lt;h3&gt;Feldinformationsliste：&lt;/h3&gt;"</span></span><span>;
</span><span><span class="hljs-keyword">while</span></span><span> (</span><span><span class="hljs-variable">$field</span></span><span> = </span><span><span class="hljs-title function_ invoke__">mysql_fetch_field</span></span><span>(</span><span><span class="hljs-variable">$result</span></span><span>)) {
    </span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"Feldname: "</span></span><span> . </span><span><span class="hljs-variable">$field</span></span><span>-&gt;name . </span><span><span class="hljs-string">"&lt;br&gt;"</span></span><span>;
    </span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"Feldtyp: "</span></span><span> . </span><span><span class="hljs-variable">$field</span></span><span>-&gt;type . </span><span><span class="hljs-string">"&lt;br&gt;"</span></span><span>;
    </span><span><span class="hljs-comment">// 4. verwendenmysql_field_lenFeldlänge erhalten</span></span><span>
    </span><span><span class="hljs-variable">$length</span></span><span> = </span><span><span class="hljs-title function_ invoke__">mysql_field_len</span></span><span>(</span><span><span class="hljs-variable">$result</span></span><span>, </span><span><span class="hljs-variable">$field</span></span><span>-&gt;orgname ? </span><span><span class="hljs-variable">$field</span></span><span>-&gt;orgname : </span><span><span class="hljs-variable">$field</span></span><span>-&gt;name);
    </span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"Feldlänge: "</span></span><span> . </span><span><span class="hljs-variable">$length</span></span><span> . </span><span><span class="hljs-string">"&lt;br&gt;&lt;hr&gt;"</span></span><span>;
}

<span class="hljs-comment">/*
Dinge zu beachten：
1. mysql_* Die Serienfunktionen sind PHP 7 Die obigen Versionen wurden veraltet，建议verwenden mysqli oder PDO。
2. mysql_field_len Gibt die maximale Bytelänge des Feldes zurück，Nicht die Anzahl der Zeichen，Achten Sie auf Multibyte -Charakter -Sets。
3. mysql_fetch_field Sie können die Details des Feldes erhalten，Enthält Typen、Länge、Standardwert usw.。
*/</span>

</span><span><span class="hljs-meta">?&gt;</span></span><span>
</span></span>

<hr>

 <span><span><span class="hljs-meta">&lt;?php</span></span><span>
</span><span><span class="hljs-comment">// 尾部无关Codebeispiel</span></span><span>
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"Danke, dass du diesen Artikel gelesen hast！&lt;br&gt;"</span></span><span>;
</span><span><span class="hljs-meta">?&gt;</span></span><span>
</span></span>

mysql_field_len

Ähnlich

Beispiel für die Verwendung von MySQL_Field_len mit MySQL_Fetch_Field