{"title":"FAQ：数据库和模型","version":"4.1","locale":"zh-hans","docname":"faq/models","url":"/zh-hans/4.1/faq/models/","canonical":"https://djangodocs.dev/zh-hans/4.1/faq/models/","summary":"首先确保你的 Django DEBUG 选项为 True。","html":"<h1>FAQ：数据库和模型<a class=\"heading-anchor\" href=\"#faq-databases-and-models\"><span class=\"visually-hidden\">Link to this heading</span><span aria-hidden=\"true\">#</span></a></h1>\n<section id=\"how-can-i-see-the-raw-sql-queries-django-is-running\">\n<span id=\"faq-see-raw-sql-queries\"></span><h2>我该如何在Django运行的过程中看到SQL查询？<a class=\"heading-anchor\" href=\"#how-can-i-see-the-raw-sql-queries-django-is-running\"><span class=\"visually-hidden\">Link to this heading</span><span aria-hidden=\"true\">#</span></a></h2>\n<p>首先确保你的 Django <a class=\"reference internal\" href=\"/zh-hans/4.1/ref/settings/#std-setting-DEBUG\"><code class=\"xref std std-setting docutils literal notranslate\">DEBUG</code></a> 选项为 <code class=\"docutils literal notranslate\">True</code>。然后，这样做：</p>\n<div class=\"code-block\" data-language=\"default\"><div class=\"code-block-toolbar\"><span class=\"code-block-language\">Code</span><button type=\"button\" class=\"copy-button\" data-copy hidden><span class=\"copy-button-label\">Copy</span></button></div><pre role=\"group\" tabindex=\"0\" aria-label=\"Code code\"><code><span class=\"gp\">&gt;&gt;&gt; </span><span class=\"kn\">from</span> <span class=\"nn\">django.db</span> <span class=\"kn\">import</span> connection\n<span class=\"gp\">&gt;&gt;&gt; </span>connection<span class=\"o\">.</span>queries\n<span class=\"go\">[{&#39;sql&#39;: &#39;SELECT polls_polls.id, polls_polls.question, polls_polls.pub_date FROM polls_polls&#39;,</span>\n<span class=\"go\">&#39;time&#39;: &#39;0.002&#39;}]</span>\n</code></pre></div>\n<p><code class=\"docutils literal notranslate\">connection.queries</code> 只有在 <a class=\"reference internal\" href=\"/zh-hans/4.1/ref/settings/#std-setting-DEBUG\"><code class=\"xref std std-setting docutils literal notranslate\">DEBUG</code></a> 为 <a href=\"#id1\"><span class=\"problematic\" id=\"id2\">``</span></a>True``时才可用. 它是按顺序执行的字典列表，每个字典包括:</p>\n<div class=\"code-block\" data-language=\"default\"><div class=\"code-block-toolbar\"><span class=\"code-block-language\">Code</span><button type=\"button\" class=\"copy-button\" data-copy hidden><span class=\"copy-button-label\">Copy</span></button></div><pre role=\"group\" tabindex=\"0\" aria-label=\"Code code\"><code>``sql`` -- The raw SQL statement\n``time`` -- How long the statement took to execute, in seconds.\n</code></pre></div>\n<p><code class=\"docutils literal notranslate\">connection.queries</code> 包含了所有的SQL 语句 -- INSERT, UPDATES, SELECT, 等. 每次你的应用访问了数据库，查询都会被记录下来。</p>\n<p>如果你在使用 <span class=\"xref std std-doc\">multiple databases1</span>，你可以对 <code class=\"docutils literal notranslate\">connections</code> 字典的每个成员使用相同的接口:</p>\n<div class=\"code-block\" data-language=\"default\"><div class=\"code-block-toolbar\"><span class=\"code-block-language\">Code</span><button type=\"button\" class=\"copy-button\" data-copy hidden><span class=\"copy-button-label\">Copy</span></button></div><pre role=\"group\" tabindex=\"0\" aria-label=\"Code code\"><code><span class=\"gp\">&gt;&gt;&gt; </span><span class=\"kn\">from</span> <span class=\"nn\">django.db</span> <span class=\"kn\">import</span> connections\n<span class=\"gp\">&gt;&gt;&gt; </span>connections<span class=\"p\">[</span><span class=\"s1\">&#39;my_db_alias&#39;</span><span class=\"p\">]</span><span class=\"o\">.</span>queries\n</code></pre></div>\n<p>如果需要在函数中的任何位置手动清除查询列表，只需要调用 <code class=\"docutils literal notranslate\">reset_queries()</code>，像这样：</p>\n<div class=\"code-block\" data-language=\"default\"><div class=\"code-block-toolbar\"><span class=\"code-block-language\">Code</span><button type=\"button\" class=\"copy-button\" data-copy hidden><span class=\"copy-button-label\">Copy</span></button></div><pre role=\"group\" tabindex=\"0\" aria-label=\"Code code\"><code><span class=\"kn\">from</span> <span class=\"nn\">django.db</span> <span class=\"kn\">import</span> reset_queries\nreset_queries<span class=\"p\">()</span>\n</code></pre></div>\n</section>\n<section id=\"can-i-use-django-with-a-preexisting-database\">\n<h2>Can I use Django with a preexisting database?<a class=\"heading-anchor\" href=\"#can-i-use-django-with-a-preexisting-database\"><span class=\"visually-hidden\">Link to this heading</span><span aria-hidden=\"true\">#</span></a></h2>\n<p>是的，可以看这篇文档 <a class=\"reference internal\" href=\"/zh-hans/4.1/howto/legacy-databases/\"><span class=\"doc\">导入已有数据库</span></a>。</p>\n</section>\n<section id=\"if-i-make-changes-to-a-model-how-do-i-update-the-database\">\n<h2>如果我对一个模型做了改动，我该如何去更新数据库？<a class=\"heading-anchor\" href=\"#if-i-make-changes-to-a-model-how-do-i-update-the-database\"><span class=\"visually-hidden\">Link to this heading</span><span aria-hidden=\"true\">#</span></a></h2>\n<p>看看Django对数据模型改动的支持：<a class=\"reference internal\" href=\"/zh-hans/4.1/topics/migrations/#module-django.db.migrations\" title=\"django.db.migrations: Schema migration support for Django models\"><code class=\"xref py py-mod docutils literal notranslate\">schema migrations</code></a> （模型迁移）</p>\n<p>如果你不介意清除数据，工程目录下的 <code class=\"docutils literal notranslate\">manage.py</code> 工具使用 <a class=\"reference internal\" href=\"/zh-hans/4.1/ref/django-admin/#django-admin-flush\"><code class=\"xref std std-djadmin docutils literal notranslate\">flush</code></a> 选项去立即重置数据库到 执行 <a class=\"reference internal\" href=\"/zh-hans/4.1/ref/django-admin/#django-admin-migrate\"><code class=\"xref std std-djadmin docutils literal notranslate\">migrate</code></a> 后的状态</p>\n</section>\n<section id=\"do-django-models-support-multiple-column-primary-keys\">\n<h2>Django 支持多列主键吗？<a class=\"heading-anchor\" href=\"#do-django-models-support-multiple-column-primary-keys\"><span class=\"visually-hidden\">Link to this heading</span><span aria-hidden=\"true\">#</span></a></h2>\n<p>不，只支持单列主键。</p>\n<p>但这在实践中并不是一个问题，因为无法阻止你添加其他的约束（使用 <code class=\"docutils literal notranslate\">unique_together</code> 模型选项或者在你的数据库中直接创建约束），并在这一级上强化唯一性。管理界面需要单列主键才能工作；例如，你需要唯一值来指定要编辑或删除的对象。</p>\n</section>\n<section id=\"does-django-support-nosql-databases\">\n<h2>Django 支持 NoSQL 数据库吗？<a class=\"heading-anchor\" href=\"#does-django-support-nosql-databases\"><span class=\"visually-hidden\">Link to this heading</span><span aria-hidden=\"true\">#</span></a></h2>\n<p>Django 官方不支持 NoSQL 数据库，不过有一些项目和拷贝向 Django 中添加了 NoSQL 的功能，如：<a href=\"#id1\"><span class=\"problematic\" id=\"id2\">`Django non-rel`_</span></a> 。</p>\n<p>你可以查看 <a class=\"reference external\" href=\"https://code.djangoproject.com/wiki/NoSqlSupport\">the wiki page</a> 来探讨一些其他方案。</p>\n</section>\n<section id=\"how-do-i-add-database-specific-options-to-my-create-table-statements-such-as-specifying-myisam-as-the-table-type\">\n<h2>如何将特定于数据库的选项添加到我的 CREATE TABLE 语句中，例如将 MylSAM 指定为表类型？<a class=\"heading-anchor\" href=\"#how-do-i-add-database-specific-options-to-my-create-table-statements-such-as-specifying-myisam-as-the-table-type\"><span class=\"visually-hidden\">Link to this heading</span><span aria-hidden=\"true\">#</span></a></h2>\n<p>我们尽量避免在 Django 代码中添加特例来容纳所有特定于数据库的选项，如表数据等。如果您想使用这些选项中的任何一个，请使用：class : ~ django.db.migrations.operations.RunSQL  操作来创建迁移，包含＂ALTER TABLE＂语句，它们可以执行您想要的操作。</p>\n<p>例如，如果你使用 MySQL 并且你想让你的数据表使用 MyISAM 表类型，使用如下 SQL 语句：</p>\n<div class=\"code-block\" data-language=\"default\"><div class=\"code-block-toolbar\"><span class=\"code-block-language\">Code</span><button type=\"button\" class=\"copy-button\" data-copy hidden><span class=\"copy-button-label\">Copy</span></button></div><pre role=\"group\" tabindex=\"0\" aria-label=\"Code code\"><code>ALTER TABLE myapp_mytable ENGINE<span class=\"o\">=</span>MyISAM<span class=\"p\">;</span>\n</code></pre></div>\n</section>","rootId":"faq-databases-and-models","toc":[{"title":"我该如何在Django运行的过程中看到SQL查询？","anchor":"how-can-i-see-the-raw-sql-queries-django-is-running","children":[]},{"title":"Can I use Django with a preexisting database?","anchor":"can-i-use-django-with-a-preexisting-database","children":[]},{"title":"如果我对一个模型做了改动，我该如何去更新数据库？","anchor":"if-i-make-changes-to-a-model-how-do-i-update-the-database","children":[]},{"title":"Django 支持多列主键吗？","anchor":"do-django-models-support-multiple-column-primary-keys","children":[]},{"title":"Django 支持 NoSQL 数据库吗？","anchor":"does-django-support-nosql-databases","children":[]},{"title":"如何将特定于数据库的选项添加到我的 CREATE TABLE 语句中，例如将 MylSAM 指定为表类型？","anchor":"how-do-i-add-database-specific-options-to-my-create-table-statements-such-as-specifying-myisam-as-the-table-type","children":[]}],"breadcrumbs":[{"docname":"faq/index","title":"Django FAQ","url":"/zh-hans/4.1/faq/"}],"prev":{"docname":"faq/help","title":"FAQ：获取帮助","url":"/zh-hans/4.1/faq/help/"},"next":{"docname":"faq/admin","title":"FAQ：管理","url":"/zh-hans/4.1/faq/admin/"},"formats":{"html":"/zh-hans/4.1/faq/models/","markdown":"/zh-hans/4.1/faq/models.md","json":"/zh-hans/4.1/faq/models.json"},"source":"https://github.com/django/django/blob/stable/4.1.x/docs/faq/models.txt","official":"https://docs.djangoproject.com/zh-hans/4.1/faq/models/","inVersions":["6.1","6.0","5.2","5.1","5.0","4.2","4.1","4.0","3.2","3.1","3.0","2.2","2.1","2.0"],"inLocales":["en","zh-hans","fr","ja","id","it","pt-br","ko","es","el","pl"]}