blocks|key|3428864|text|您并不总是能够简单地生成迁移以获得您想要的代码。您可以创建一个空迁移，然后使用所需的代码填充它。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3428865|您可以在此处找到有关如何在迁移中完成不同任务的信息：|3428866|http://api.rubyonrails.org/classes/ActiveRecord/Migration.html|offset|length|3428867|更具体地说，您可以看到如何使用以下方法删除一个表：|3428868|drop_table+:table_name|code-block|syntax|javascript|3428869|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|0|1Q|0|0|0|0^^$0|@$1|2|3|4|5|6|7|V|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|W|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|X|8|@]|9|@$F|Y|G|Z|1|10]]|A|$]]|$1|H|3|I|5|6|7|11|8|@]|9|@]|A|$]]|$1|J|3|K|5|L|7|12|8|@]|9|@]|A|$M|N]]|$1|O|3|-4|5|6|7|13|8|@]|9|@]|A|$]]]|P|$Q|$5|R|S|T|A|$U|E]]]]

You won't always be able to simply generate the migration to already have the code you want. You can create an empty migration and then populate it with the code you need.

You can find information about how to accomplish different tasks in a migration here:

<a href="http://api.rubyonrails.org/classes/ActiveRecord/Migration.html" rel="noreferrer">http://api.rubyonrails.org/classes/ActiveRecord/Migration.html</a>

More specifically, you can see how to drop a table using the following approach:

<pre><code>drop_table :table_name
</code></pre>

blocks|key|1980856|text|我认为，要完全“正式”，你需要创建一个新的迁移，并将drop_table放在self.up中。然后，self.down方法应该包含用于完全重新创建表的所有代码。在创建迁移时，这些代码可能只是从schema.rb获取的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1980857|放入代码来创建一个您知道不再需要的表，这似乎有点奇怪，但这将保持所有迁移代码的完整性和“正式”，对吧？|1980858|我只是为了一张我需要掉下来的桌子这样做，但老实说，我并没有测试“向下”，也不确定为什么我会这样做。|1980859|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|H|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|I|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|J|8|@]|9|@]|A|$]]|$1|F|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|G|$]]

I think, to be completely "official", you would need to create a new migration, and put drop_table in self.up. The self.down method should then contain all the code to recreate the table in full. Presumably that code could just be taken from schema.rb at the time you create the migration.

It seems a little odd, to put in code to create a table you know you aren't going to need anymore, but that would keep all the migration code complete and "official", right?

I just did this for a table I needed to drop, but honestly didn't test the "down" and not sure why I would.

blocks|key|4840360|text|首先，使用您喜欢的名称生成一个空迁移。这样做很重要，因为它创建了适当的日期。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4840361|rails+generate+migration+DropProductsTable|code-block|syntax|javascript|4840362|这将在/db/+.rb+/中生成一个类似于20111015185025_drop_products_table.rb的迁移文件|4840363|现在，将该文件编辑为如下所示：|4840364|class+DropProductsTable+<+ActiveRecord::Migration
++def+up
++++drop_table+:products
++end

++def+down
++++raise+ActiveRecord::IrreversibleMigration
++end
end|4840365|我唯一添加的是drop_table+:products和raise+ActiveRecord::IrreversibleMigration。|offset|length|style|CODE|4840366|然后运行rake+db:migrate，它将为您删除该表。|4840367|entityMap^0|0|0|0|0|0|7|K|S|15|0|4|F|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Y|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|Z|8|@]|9|@]|A|$]]|$1|K|3|L|5|D|7|10|8|@]|9|@]|A|$E|F]]|$1|M|3|N|5|6|7|11|8|@$O|12|P|13|Q|R]|$O|14|P|15|Q|R]]|9|@]|A|$]]|$1|S|3|T|5|6|7|16|8|@$O|17|P|18|Q|R]]|9|@]|A|$]]|$1|U|3|-4|5|6|7|19|8|@]|9|@]|A|$]]]|V|$]]

First generate an empty migration with any name you'd like. It's important to do it this way since it creates the appropriate date.

<pre><code>rails generate migration DropProductsTable
</code></pre>

This will generate a .rb file in /db/migrate/ like 20111015185025_drop_products_table.rb

Now edit that file to look like this:

<pre><code>class DropProductsTable &lt; ActiveRecord::Migration
 def up
 drop_table :products
 end

 def down
 raise ActiveRecord::IrreversibleMigration
 end
end
</code></pre>

The only thing I added was <code>drop_table :products</code> and <code>raise ActiveRecord::IrreversibleMigration</code>.

Then run <code>rake db:migrate</code> and it'll drop the table for you.

blocks|key|3428977|text|警告：这样做的风险自负，正如@z-atef和@nzifnab正确指出的那样，Rails将不会意识到这些更改，您的迁移序列填充失败，并且您的模式将与您的同事的不同。这是一个仅供本地修补开发的资源。|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|3428978|3428979|虽然这里提供的答案工作正常，但我想要一些更“简单”的东西，我在这里找到了：link+First进入rails控制台：|3428980|$rails+console|code-block|syntax|javascript|3428981|然后只需键入：|3428982|ActiveRecord::Migration.drop_table(:table_name)|3428983|完成了，为我工作！|3428984|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/users/2052097/z-atef|1|https://stackoverflow.com/users/649006/nzifnab|2|http://problemateek.blogspot.com.es/2012/07/drop-table-from-rails-console.html^0|0|2|F|6|0|N|7|1|0|0|11|4|2|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|15|8|@$9|16|A|17|B|C]]|D|@$9|18|A|19|1|1A]|$9|1B|A|1C|1|1D]]|E|$]]|$1|F|3|-4|5|6|7|1E|8|@]|D|@]|E|$]]|$1|G|3|H|5|6|7|1F|8|@]|D|@$9|1G|A|1H|1|1I]]|E|$]]|$1|I|3|J|5|K|7|1J|8|@]|D|@]|E|$L|M]]|$1|N|3|O|5|6|7|1K|8|@]|D|@]|E|$]]|$1|P|3|Q|5|K|7|1L|8|@]|D|@]|E|$L|M]]|$1|R|3|S|5|6|7|1M|8|@]|D|@]|E|$]]|$1|T|3|-4|5|6|7|1N|8|@]|D|@]|E|$]]]|U|$V|$5|W|X|Y|E|$Z|10]]|11|$5|W|X|Y|E|$Z|12]]|13|$5|W|X|Y|E|$Z|14]]]]

Warning: Do this at your own risk, as @<a href="https://stackoverflow.com/users/2052097/z-atef">z-atef</a> and @<a href="https://stackoverflow.com/users/649006/nzifnab">nzifnab</a> correctly point out, Rails will not be aware of these changes, your migration sequence fill fail and your schema will be different from your coworkers'. This is meant as a resource for locally tinkering with development only.
<hr />
While the answers provided here work properly, I wanted something a bit more 'straightforward', I found it here: <a href="http://problemateek.blogspot.com.es/2012/07/drop-table-from-rails-console.html" rel="nofollow noreferrer">link</a>
First enter rails console:
<pre><code>$rails console
</code></pre>
Then just type:
<pre><code>ActiveRecord::Migration.drop_table(:table_name)
</code></pre>
And done, worked for me!

blocks|key|1231335|text|打开rails控制台|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1231336|ActiveRecord::Base.connection.execute("drop+table+table_name")|code-block|syntax|javascript|1231337|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Open you rails console

<pre><code>ActiveRecord::Base.connection.execute("drop table table_name")
</code></pre>

blocks|key|1231348|text|我需要删除我们的迁移脚本以及表本身...|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1231349|class+Util::Table+<+ActiveRecord::Migration

+def+self.clobber(table_name)+++
++++#+drop+the+table
++++if+ActiveRecord::Base.connection.table_exists?+table_name
++++++puts+"\n==+"+%2B+table_name.upcase.cyan+%2B+"+!+"+
+++++++++++<<+Time.now.strftime("%25H:%25M:%25S").yellow
++++++drop_table+table_name+
++++end

++++#+locate+any+existing+migrations+for+a+table+and+delete+them
++++base_folder+=+File.join(Rails.root.to_s,+'db',+'migrate')
++++Dir[File.join(base_folder,+'**',+'*.rb')].each+do+%7Cfile%7C
++++++if+file+=~+/create_#{table_name}.rb/
++++++++puts+"==+deleting+migration:+"+%2B+file.cyan+%2B+"+!+"
+++++++++++++<<+Time.now.strftime("%25H:%25M:%25S").yellow
++++++++FileUtils.rm_rf(file)
++++++++break
++++++end
++++end
++end

++def+self.clobber_all
++++#+delete+every+table+in+the+db,+along+with+every+corresponding+migration+
++++ActiveRecord::Base.connection.tables.each+{%7Ct%7C+clobber+t}
++end

end|code-block|syntax|javascript|1231350|在终端窗口中运行：|1231351|$+rails+runner+"Util::Table.clobber+'your_table_name'"|1231352|或|1231353|$+rails+runner+"Util::Table.clobber_all"|1231354|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|U|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

I needed to delete our migration scripts along with the tables themselves ...

<pre><code>class Util::Table &lt; ActiveRecord::Migration

 def self.clobber(table_name) 
 # drop the table
 if ActiveRecord::Base.connection.table_exists? table_name
 puts "\n== " + table_name.upcase.cyan + " ! " 
 &lt;&lt; Time.now.strftime("%H:%M:%S").yellow
 drop_table table_name 
 end

 # locate any existing migrations for a table and delete them
 base_folder = File.join(Rails.root.to_s, 'db', 'migrate')
 Dir[File.join(base_folder, '**', '*.rb')].each do |file|
 if file =~ /create_#{table_name}.rb/
 puts "== deleting migration: " + file.cyan + " ! "
 &lt;&lt; Time.now.strftime("%H:%M:%S").yellow
 FileUtils.rm_rf(file)
 break
 end
 end
 end

 def self.clobber_all
 # delete every table in the db, along with every corresponding migration 
 ActiveRecord::Base.connection.tables.each {|t| clobber t}
 end

end
</code></pre>

from terminal window run:

<pre><code>$ rails runner "Util::Table.clobber 'your_table_name'"
</code></pre>

or

<pre><code>$ rails runner "Util::Table.clobber_all"
</code></pre>

blocks|key|4840491|text|ActiveRecord::Base.connection.drop_table+:table_name|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4840492|entityMap^0|0|1G|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|K|8|@]|D|@]|E|$]]]|G|$]]

<code>ActiveRecord::Base.connection.drop_table :table_name</code>

blocks|key|1976505|text|您需要使用以下命令创建一个新的迁移文件|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1976506|rails+generate+migration+drop_table_xyz|code-block|syntax|javascript|1976507|并在新生成的迁移文件(db/+drop_table+/xxxxxxx_drop_table_xyz)中编写表代码，如下所示|1976508|drop_table+:tablename|1976509|或者，如果您希望在不进行迁移的情况下删除表，只需通过以下命令打开rails控制台|1976510|$+rails+c|1976511|并执行以下命令|1976512|ActiveRecord::Base.connection.execute("drop+table+table_name")|1976513|或者，您可以使用更简化的命令|1976514|ActiveRecord::Migration.drop_table(:table_name)|1976515|entityMap^0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|Z|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|10|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|11|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|12|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|13|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|14|8|@]|9|@]|A|$]]|$1|Q|3|R|5|D|7|15|8|@]|9|@]|A|$E|F]]|$1|S|3|T|5|6|7|16|8|@]|9|@]|A|$]]|$1|U|3|V|5|D|7|17|8|@]|9|@]|A|$E|F]]|$1|W|3|-4|5|6|7|18|8|@]|9|@]|A|$]]]|X|$]]

You need to to create a new migration file using following command

<pre><code>rails generate migration drop_table_xyz
</code></pre>

and write drop_table code in newly generated migration file (db/migration/xxxxxxx_drop_table_xyz) like

<pre><code>drop_table :tablename
</code></pre>

Or if you wanted to drop table without migration, simply open rails console by

<pre><code>$ rails c
</code></pre>

and execute following command

<pre><code>ActiveRecord::Base.connection.execute("drop table table_name")
</code></pre>

or you can use more simplified command

<pre><code>ActiveRecord::Migration.drop_table(:table_name)
</code></pre>

blocks|key|1231403|text|手动编写您的迁移。例如，运行rails+g+migration+DropUsers。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1231404|至于迁移的代码，我将引用Maxwell+Holder的帖子Rails+Migration+Checklist|1231405|运行错误的rake+db:migrate，然后rake+db:rollback将失败|1231406|class+DropUsers+<+ActiveRecord::Migration
++def+change
++++drop_table+:users
++end
end|code-block|syntax|javascript|1231407|GOOD+-显示迁移不应可逆的意图|1231408|class+DropUsers+<+ActiveRecord::Migration
++def+up
++++drop_table+:users
++end

++def+down
++++fail+ActiveRecord::IrreversibleMigration
++end
end|1231409|更好-实际上是可逆的|1231410|class+DropUsers+<+ActiveRecord::Migration
++def+change
++++drop_table+:users+do+%7Ct%7C
++++++t.string+:email,+null:+false
++++++t.timestamps+null:+false
++++end
++end
end|1231411|entityMap|0|LINK|mutability|MUTABLE|url|http://maxwellholder.com/blog/rails-migration-checklist^0|E|R|0|T|P|0|0|5|F|N|G|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|14|8|@$9|15|A|16|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|17|8|@]|D|@$9|18|A|19|1|1A]]|E|$]]|$1|H|3|I|5|6|7|1B|8|@$9|1C|A|1D|B|C]|$9|1E|A|1F|B|C]]|D|@]|E|$]]|$1|J|3|K|5|L|7|1G|8|@]|D|@]|E|$M|N]]|$1|O|3|P|5|6|7|1H|8|@]|D|@]|E|$]]|$1|Q|3|R|5|L|7|1I|8|@]|D|@]|E|$M|N]]|$1|S|3|T|5|6|7|1J|8|@]|D|@]|E|$]]|$1|U|3|V|5|L|7|1K|8|@]|D|@]|E|$M|N]]|$1|W|3|-4|5|6|7|1L|8|@]|D|@]|E|$]]]|X|$Y|$5|Z|10|11|E|$12|13]]]]

Write your migration manually. E.g. run <code>rails g migration DropUsers</code>.

As for the code of the migration I'm just gonna quote Maxwell Holder's post <a href="http://maxwellholder.com/blog/rails-migration-checklist">Rails Migration Checklist</a>

<h1>BAD - running <code>rake db:migrate</code> and then <code>rake db:rollback</code> will fail</h1>

<pre><code>class DropUsers &lt; ActiveRecord::Migration
 def change
 drop_table :users
 end
end
</code></pre>

<h1>GOOD - reveals intent that migration should not be reversible</h1>

<pre><code>class DropUsers &lt; ActiveRecord::Migration
 def up
 drop_table :users
 end

 def down
 fail ActiveRecord::IrreversibleMigration
 end
end
</code></pre>

<h1>BETTER - is actually reversible</h1>

<pre><code>class DropUsers &lt; ActiveRecord::Migration
 def change
 drop_table :users do |t|
 t.string :email, null: false
 t.timestamps null: false
 end
 end
end
</code></pre>

blocks|key|4840592|text|迁移rails+g+drop_users|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4840593|edit+|unordered-list-item|4840594|ordered-list-item|4840595|4840596|4840597|++++class+DropUsers+<+ActiveRecord::Migration
++++++def+change
++++++++drop_table+:users+do+%7Ct%7C
++++++++++t.string+:name
++++++++++t.timestamps
++++++++end
++++++end
++++end|code-block|syntax|javascript|4840598|4840599|rake+db:迁移|4840600|4840601|entityMap^0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|T|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|U|8|@]|9|@]|A|$]]|$1|E|3|-4|5|F|7|V|8|@]|9|@]|A|$]]|$1|G|3|-4|5|6|7|W|8|@]|9|@]|A|$]]|$1|H|3|-4|5|6|7|X|8|@]|9|@]|A|$]]|$1|I|3|J|5|K|7|Y|8|@]|9|@]|A|$L|M]]|$1|N|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]|$1|O|3|P|5|F|7|10|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|11|8|@]|9|@]|A|$]]|$1|R|3|-4|5|6|7|12|8|@]|9|@]|A|$]]]|S|$]]

<ol>
<li>rails g migration drop_users</li>
<li>edit the migration</li>
</ol>

<pre class="lang-ruby prettyprint-override"><code> class DropUsers &lt; ActiveRecord::Migration
 def change
 drop_table :users do |t|
 t.string :name
 t.timestamps
 end
 end
 end
</code></pre>

<ol start="3">
<li>rake db:migrate</li>
</ol>

blocks|key|3429168|text|跑|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3429169|rake+db:migrate:down+VERSION=<version>|code-block|syntax|javascript|3429170|其中，<version>是要恢复的迁移文件的版本号。|offset|length|style|CODE|3429171|示例：-|3429172|rake+db:migrate:down+VERSION=3846656238|3429173|entityMap^0|0|0|3|9|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@$I|V|J|W|K|L]]|9|@]|A|$]]|$1|M|3|N|5|6|7|X|8|@]|9|@]|A|$]]|$1|O|3|P|5|D|7|Y|8|@]|9|@]|A|$E|F]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

Run

<pre><code>rake db:migrate:down VERSION=&lt;version&gt;
</code></pre>

Where <code>&lt;version&gt;</code> is the version number of your migration file you want to revert.

Example:-

<pre><code>rake db:migrate:down VERSION=3846656238
</code></pre>

blocks|key|4840628|text|你能做的最好的方法就是|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4840629|rails+g+migration+Drop_table_Users|code-block|syntax|javascript|4840630|然后执行以下操作|4840631|rake+db:migrate|4840632|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

the best way you can do is 

<pre><code>rails g migration Drop_table_Users
</code></pre>

then do the following

<pre><code>rake db:migrate
</code></pre>

blocks|key|1234002|text|您可以简单地从rails控制台中删除一个表。首先打开控制台|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1234003|$+rails+c|code-block|syntax|javascript|1234004|然后在控制台中粘贴此命令|1234005|ActiveRecord::Migration.drop_table(:table_name)|1234006|将table_name替换为要删除的表。|offset|length|style|BOLD|1234007|您也可以直接从终端删除table。只需输入应用程序的根目录并运行以下命令|1234008|$+rails+runner+"Util::Table.clobber+'table_name'"|1234009|entityMap^0|0|0|0|0|1|A|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Y|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|Z|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|10|8|@$M|11|N|12|O|P]]|9|@]|A|$]]|$1|Q|3|R|5|6|7|13|8|@]|9|@]|A|$]]|$1|S|3|T|5|D|7|14|8|@]|9|@]|A|$E|F]]|$1|U|3|-4|5|6|7|15|8|@]|9|@]|A|$]]]|V|$]]

you can simply drop a table from rails console.
first open the console

<pre><code>$ rails c
</code></pre>

then paste this command in console

<pre><code>ActiveRecord::Migration.drop_table(:table_name)
</code></pre>

replace table_name with the table you want to delete.

you can also drop table directly from the terminal. just enter in the root directory of your application and run this command

<pre><code>$ rails runner "Util::Table.clobber 'table_name'"
</code></pre>

blocks|key|4840680|text|运行以下命令：-|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|4840681|rails+g+migration+drop_table_name|code-block|syntax|javascript|4840682|然后：|4840683|rake+db:migrate|4840684|，或者如果您使用的是MySql数据库，则：|4840685|使用database|4840686|show+databases;|unordered-list-item|CODE|4840687|
|4840688|show+tables;|4840689|4840690|drop+table_name;|4840691|
登录|4840692|ordered-list-item|4840693|4840694|entityMap^0|0|8|0|0|0|0|0|L|0|0|0|F|0|0|0|C|0|0|0|G|0|0|0|0^^$0|@$1|2|3|4|5|6|7|1A|8|@$9|1B|A|1C|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|1D|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|1E|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|1F|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|1G|8|@$9|1H|A|1I|B|C]]|D|@]|E|$]]|$1|Q|3|R|5|6|7|1J|8|@]|D|@]|E|$]]|$1|S|3|T|5|U|7|1K|8|@$9|1L|A|1M|B|V]]|D|@]|E|$]]|$1|W|3|X|5|6|7|1N|8|@]|D|@]|E|$]]|$1|Y|3|Z|5|U|7|1O|8|@$9|1P|A|1Q|B|V]]|D|@]|E|$]]|$1|10|3|X|5|6|7|1R|8|@]|D|@]|E|$]]|$1|11|3|12|5|U|7|1S|8|@$9|1T|A|1U|B|V]]|D|@]|E|$]]|$1|13|3|14|5|6|7|1V|8|@]|D|@]|E|$]]|$1|15|3|-4|5|16|7|1W|8|@]|D|@]|E|$]]|$1|17|3|-4|5|6|7|1X|8|@]|D|@]|E|$]]|$1|18|3|-4|5|6|7|1Y|8|@]|D|@]|E|$]]]|19|$]]

Run this command:-

<pre><code>rails g migration drop_table_name
</code></pre>

then:

<pre><code>rake db:migrate
</code></pre>

or if you are using MySql database then:

<ol>
<li>login with database</li>
<li><code>show databases;</code></li>
<li><code>show tables;</code></li>
<li><code>drop table_name;</code></li>
</ol>

blocks|key|3429263|text|您可以按照指南中的方式回滚迁移：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3429264|http://guides.rubyonrails.org/active_record_migrations.html#reverting-previous-migrations|offset|length|3429265|生成迁移：|3429266|rails+generate+migration+revert_create_tablename|code-block|syntax|javascript|3429267|编写迁移：|3429268|require_relative+'20121212123456_create_tablename'

class+RevertCreateTablename+<+ActiveRecord::Migration[5.0]
++def+change
++++revert+CreateTablename++++
++end
end|3429269|通过这种方式，您还可以回滚，并可以使用恢复任何迁移|3429270|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|2H|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Z|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|10|8|@]|9|@$D|11|E|12|1|13]]|A|$]]|$1|F|3|G|5|6|7|14|8|@]|9|@]|A|$]]|$1|H|3|I|5|J|7|15|8|@]|9|@]|A|$K|L]]|$1|M|3|N|5|6|7|16|8|@]|9|@]|A|$]]|$1|O|3|P|5|J|7|17|8|@]|9|@]|A|$K|L]]|$1|Q|3|R|5|6|7|18|8|@]|9|@]|A|$]]|$1|S|3|-4|5|6|7|19|8|@]|9|@]|A|$]]]|T|$U|$5|V|W|X|A|$Y|C]]]]

You can roll back a migration the way it is in the guide:

<a href="http://guides.rubyonrails.org/active_record_migrations.html#reverting-previous-migrations" rel="noreferrer">http://guides.rubyonrails.org/active_record_migrations.html#reverting-previous-migrations</a>

Generate a migration:

<pre><code>rails generate migration revert_create_tablename
</code></pre>

Write the migration:

<pre><code>require_relative '20121212123456_create_tablename'

class RevertCreateTablename &lt; ActiveRecord::Migration[5.0]
 def change
 revert CreateTablename 
 end
end
</code></pre>

This way you can also rollback and can use to revert any migration

blocks|key|3429301|text|简单而正式的方法是：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3429302|++rails+g+migration+drop_tablename|code-block|syntax|javascript|3429303|现在转到db/migrate，查找包含drop_tablename作为文件名的文件，并将其编辑为以下内容。|3429304|++++def+change
++++++drop_table+:table_name
++++end|3429305|然后，您需要运行|3429306|++++rake+db:migrate+|3429307|在你的控制台上。|3429308|entityMap^0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|W|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|Y|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

The simple and official way would be this:

<pre><code> rails g migration drop_tablename
</code></pre>

Now go to your db/migrate and look for your file which contains the drop_tablename as the filename and edit it to this.

<pre><code> def change
 drop_table :table_name
 end
</code></pre>

Then you need to run

<pre><code> rake db:migrate 
</code></pre>

on your console.

blocks|key|4840771|text|除了引发异常或尝试重新创建现在为空的表之外-同时仍然启用迁移回滚、重做等-|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4840772|def+change
++drop_table(:users,+force:+true)+if+ActiveRecord::Base.connection.tables.include?('users')
end|code-block|syntax|javascript|4840773|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Alternative to raising exception or attempting to recreate a now empty table - while still enabling migration rollback, redo etc -

<pre><code>def change
 drop_table(:users, force: true) if ActiveRecord::Base.connection.tables.include?('users')
end
</code></pre>

blocks|key|1234097|text|Drop表/迁移|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|1234098|运行：-$+rails生成迁移DropTablename|1234099|exp:-+$+rails生成迁移DropProducts|1234100|entityMap^0|0|8|0|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@$9|M|A|N|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|O|8|@]|D|@]|E|$]]|$1|H|3|I|5|6|7|P|8|@]|D|@]|E|$]]|$1|J|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|K|$]]

Drop Table/Migration

run:-
$ rails generate migration DropTablename

exp:- $ rails generate migration DropProducts

blocks|key|4840843|text|如果你想删除一个特定表，你可以这样做|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4840844|$+rails+db:migrate:up+VERSION=[Here+you+can+insert+timestamp+of+table]|code-block|syntax|javascript|4840845|否则，如果您想删除所有数据库，您可以这样做|4840846|$rails+db:drop|4840847|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

if you want to drop a specific table you can do

<pre><code>$ rails db:migrate:up VERSION=[Here you can insert timestamp of table]
</code></pre>

otherwise if you want to drop all your database you can do

<pre><code>$rails db:drop
</code></pre>

blocks|key|1234127|text|我无法使用迁移脚本使其工作，因此我继续使用此解决方案。使用终端进入rails控制台：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1234128|rails+c|code-block|syntax|javascript|1234129|类型|1234130|ActiveRecord::Migration.drop_table(:tablename)|1234131|对我来说效果很好。这将删除以前的表。别忘了跑步|1234132|rails+db:migrate|1234133|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|U|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

I wasn't able to make it work with migration script so I went ahead with this solution. Enter rails console using the terminal:

<pre><code>rails c
</code></pre>

Type

<pre><code>ActiveRecord::Migration.drop_table(:tablename)
</code></pre>

It works well for me. This will remove the previous table. Don't forget to run

<pre><code>rails db:migrate
</code></pre>

blocks|key|4840916|text|如果要从模式中删除该表，请执行以下操作--|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4840917|rails+db:rollback|code-block|syntax|javascript|4840918|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

If you want to delete the table from the schema perform below operation --

<pre><code>rails db:rollback
</code></pre>

blocks|key|4840962|text|如果任何人正在寻找如何在SQL中做到这一点。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4840963|从终端键入rails+dbconsole|offset|length|style|CODE|4840964|输入密码|4840965|在控制台中执行|4840966|USE+db_name;|4840967|DROP+TABLE+table_name;|4840968|exit|4840969|请不要忘记从模式中删除迁移文件和表结构|4840970|entityMap^0|0|5|F|0|0|0|0|C|0|0|M|0|0|4|0|0^^$0|@$1|2|3|4|5|6|7|V|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|W|8|@$D|X|E|Y|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|Z|8|@]|9|@]|A|$]]|$1|J|3|K|5|6|7|10|8|@]|9|@]|A|$]]|$1|L|3|M|5|6|7|11|8|@$D|12|E|13|F|G]]|9|@]|A|$]]|$1|N|3|O|5|6|7|14|8|@$D|15|E|16|F|G]]|9|@]|A|$]]|$1|P|3|Q|5|6|7|17|8|@$D|18|E|19|F|G]]|9|@]|A|$]]|$1|R|3|S|5|6|7|1A|8|@]|9|@]|A|$]]|$1|T|3|-4|5|6|7|1B|8|@]|9|@]|A|$]]]|U|$]]

if anybody is looking for how to do it in SQL. 

type <code>rails dbconsole</code> from terminal

enter password

In console do

<code>USE db_name;</code>

<code>DROP TABLE table_name;</code>

<code>exit</code>

Please dont forget to remove the migration file and table structure from schema

blocks|key|1234192|text|您不能简单地运行drop_table+:table_name，而是可以通过运行以下命令创建一个空迁移：rails+g+migration+DropInstalls|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1234193|然后，您可以将其添加到该空迁移中：|1234194|class+DropInstalls+<+ActiveRecord::Migration
++def+change
++++drop_table+:installs
++end
end|code-block|syntax|javascript|1234195|然后在命令行中运行rails+db:migrate，这应该会删除Installs表找到的解决方案是here|1234196|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/a/38711180/14103174^0|8|M|1F|U|0|0|0|9|G|1D|4|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]|$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|11|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|12|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|13|8|@$9|14|A|15|B|C]]|D|@$9|16|A|17|1|18]]|E|$]]|$1|O|3|-4|5|6|7|19|8|@]|D|@]|E|$]]]|P|$Q|$5|R|S|T|E|$U|V]]]]

You can't simply run <code>drop_table :table_name</code>, instead you can create an empty migration by running:
<code>rails g migration DropInstalls</code>
You can then add this into that empty migration:
<pre><code>class DropInstalls &lt; ActiveRecord::Migration
 def change
 drop_table :installs
 end
end
</code></pre>
Then run <code>rails db:migrate</code> in the command line which should remove the Installs table
The solution was found <a href="https://stackoverflow.com/a/38711180/14103174">here</a>

I added a table that I thought I was going to need, but now no longer plan on using it. How should I remove that table?

I've already run migrations, so the table is in my database. I figure <code>rails generate migration</code> should be able to handle this, but I haven't figured out how yet.

I've tried: 

<pre><code>rails generate migration drop_tablename
</code></pre>

but that just generated an empty migration.

What is the "official" way to drop a table in Rails?

Rails DB Migration - How To Drop a Table?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我添加了一个我认为我会需要的表，但现在不再打算使用它。我该如何移走那张桌子？我已经运行了迁移，所以表在我的数据库中。我认为rails generate migration应该能够处理这件事，但我还没有弄清楚如何处理。我试过了：rails generate migration drop_tablename但这只会产生一个...

问Rails数据库迁移-如何删除表？
EN

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问Rails数据库迁移-如何删除表？EN