{"title":"FAQ：数据库和模型","version":"2.1","locale":"zh-hans","docname":"faq/models","url":"/zh-hans/2.1/faq/models/","canonical":"https://djangodocs.dev/zh-hans/2.1/faq/models/","summary":"我该如何在Django运行的过程中看到SQL查询？ Link to this heading # 首先确保你的Django设置中的`DEBUG`选项为``True``. 然后， 这样做： Code Copy >>> from django.db import connection >>> connection .…","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设置中的`DEBUG`选项为``True``. 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=\"w\"> </span><span class=\"nn\">django.db</span><span class=\"w\"> </span><span class=\"kn\">import</span> <span class=\"n\">connection</span>\n<span class=\"gp\">&gt;&gt;&gt; </span><span class=\"n\">connection</span><span class=\"o\">.</span><span class=\"n\">queries</span>\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\"><span class=\"pre\">connection.queries</span></code> 只有在 <a class=\"reference internal\" href=\"/zh-hans/2.1/ref/settings/#std-setting-DEBUG\"><code class=\"xref std std-setting docutils literal notranslate\"><span class=\"pre\">DEBUG</span></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\"><span class=\"pre\">connection.queries</span></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:doc:multiple databases1,， 你可以对``connections`` 字典::中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=\"w\"> </span><span class=\"nn\">django.db</span><span class=\"w\"> </span><span class=\"kn\">import</span> <span class=\"n\">connections</span>\n<span class=\"gp\">&gt;&gt;&gt; </span><span class=\"n\">connections</span><span class=\"p\">[</span><span class=\"s1\">&#39;my_db_alias&#39;</span><span class=\"p\">]</span><span class=\"o\">.</span><span class=\"n\">queries</span>\n</code></pre></div>\n<p>如果你需要在你的函数中去手动的清空所有的查询点，只需要调用``reset_queries()``,  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=\"w\"> </span><span class=\"nn\">django.db</span><span class=\"w\"> </span><span class=\"kn\">import</span> <span class=\"n\">reset_queries</span>\n<span class=\"n\">reset_queries</span><span class=\"p\">()</span>\n</code></pre></div>\n</section>\n<section id=\"can-i-use-django-with-a-pre-existing-database\">\n<h2>我可以让Django用一个之前已经存在的数据库吗？<a class=\"heading-anchor\" href=\"#can-i-use-django-with-a-pre-existing-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：\n<span class=\"xref std std-doc\">Integrating with a legacy database 1</span>。</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/2.1/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\"><span class=\"pre\">schema</span> <span class=\"pre\">migrations</span></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``manage.py`` 工具使用 <a class=\"reference internal\" href=\"/zh-hans/2.1/ref/django-admin/#django-admin-flush\"><code class=\"xref std std-djadmin docutils literal notranslate\"><span class=\"pre\">flush</span></code></a> 选项去立即重置数据库到 执行 <a class=\"reference internal\" href=\"/zh-hans/2.1/ref/django-admin/#django-admin-migrate\"><code class=\"xref std std-djadmin docutils literal notranslate\"><span class=\"pre\">migrate</span></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\"><span class=\"pre\">unique_together</span></code> 模型选项或者在你的数据库中直接创建约束），并强化这一级别的独特性。管理员界面（admin interface）需要单列主键才能工作；例如，你需要一种能够指定要编辑或删除的对象的简单方法。</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 class=\"reference external\" href=\"http://django-nonrel.org/\">Django non-rel</a></p>\n<p>你也可以看一下`the wiki page`_ 来讨论一些替代方案。</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><span class=\"n\">ALTER</span> <span class=\"n\">TABLE</span> <span class=\"n\">myapp_mytable</span> <span class=\"n\">ENGINE</span><span class=\"o\">=</span><span class=\"n\">MyISAM</span><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":"我可以让Django用一个之前已经存在的数据库吗？","anchor":"can-i-use-django-with-a-pre-existing-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/2.1/faq/"}],"prev":{"docname":"faq/help","title":"FAQ:获取帮助","url":"/zh-hans/2.1/faq/help/"},"next":{"docname":"faq/admin","title":"FAQ: 管理","url":"/zh-hans/2.1/faq/admin/"},"formats":{"html":"/zh-hans/2.1/faq/models/","markdown":"/zh-hans/2.1/faq/models.md","json":"/zh-hans/2.1/faq/models.json"},"source":"https://github.com/django/django/blob/stable/2.1.x/docs/faq/models.txt","official":"https://docs.djangoproject.com/zh-hans/2.1/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","pt-br","ko","es","el","pl"]}