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[Comment utiliser mysql_field_len avec mysql_fetch_field? Voir l'exemple d'explication]

gitbox 2025-09-23 
<span><span><span class="hljs-meta">&lt;?php</span></span><span>
</span><span><span class="hljs-comment">// Ce n&#39;est pas lié au contenu de l&#39;articlePHPExemple de code</span></span><span>
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"Bienvenue à lire cet article！&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">"Heure actuelle："</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">/*
Titre d&#39;article：【mysql_field_lenCorrespondremysql_fetch_fieldComment l&#39;utiliser ensemble？Voyons l&#39;exemple d&#39;explication】
*/</span>

</span><span><span class="hljs-comment">// UtiliséPHPfonctionnerMySQLLorsque la base de données，Beaucoup de gens rencontreront la nécessité d&#39;obtenir la longueur du champ。</span></span><span>
</span><span><span class="hljs-comment">// Ici, nous expliqueronsmysql_field_lenComment utiliser la fonctionmysql_fetch_fieldCorrespondreutiliser。</span></span><span>

</span><span><span class="hljs-comment">// 1. Connectez-vous à la base de données</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">'La connexion de la base de données a échoué: '</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. Exécuter une requête</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">'La requête a échoué: '</span></span><span> . </span><span><span class="hljs-title function_ invoke__">mysql_error</span></span><span>());
}

</span><span><span class="hljs-comment">// 3. utilisermysql_fetch_fieldObtenir des informations sur le terrain</span></span><span>
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"&lt;h3&gt;Liste d&#39;informations sur le terrain：&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">"Nom de champ: "</span></span><span> . </span><span><span class="hljs-variable">$field</span></span><span>-&gt;name . </span><span><span class="hljs-string">"&lt;br&gt;"</span></span><span>;
    </span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"Type de terrain: "</span></span><span> . </span><span><span class="hljs-variable">$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. utilisermysql_field_lenObtenez la longueur du champ</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">$field</span></span><span>-&gt;name);
    </span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"Longueur de champ: "</span></span><span> . </span><span><span class="hljs-variable">$length</span></span><span> . </span><span><span class="hljs-string">"&lt;br&gt;&lt;hr&gt;"</span></span><span>;
}

<span class="hljs-comment">/*
Choses à noter：
1. mysql_* Les fonctions de la série sont PHP 7 Les versions ci-dessus ont été obsolètes，建议utiliser mysqli ou PDO。
2. mysql_field_len Renvoie la longueur d&#39;octet maximale du champ，Pas le nombre de caractères，Faites attention aux ensembles de caractères multilinants。
3. mysql_fetch_field Vous pouvez obtenir les détails du champ，Comprend les types、longueur、Valeur par défaut, etc.。
*/</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Exemple de code</span></span><span>
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"Merci d&#39;avoir lu cet article！&lt;br&gt;"</span></span><span>;
</span><span><span class="hljs-meta">?&gt;</span></span><span>
</span></span>
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