mysql数据库 text类型的长度限制,使用change_column来进行长度的修改并不影响原有数据
在我的概念中，mysql中的text字段应该是没有长度限制的，但是今天事实告诉我，text类型的长度是有限制的。其中mysql的text类型有64K长度限制的，MEDIUMTEXT中型是2G，LONGTEXT大型是4G .
Creating MEDIUMTEXT columns in MySQL using Rails
Adapted from http://HdhCmsTestdepixelate测试数据/2008/5/24/rails-migrations-for-large-text-columns :
create_table :foo do |t|
...
t.text :new_col, :limit => 64.kilobytes + 1
...
end
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Leave a Comment Creating MEDIUMTEXT columns in MySQL using Rails
Adapted from http://HdhCmsTestdepixelate测试数据/2008/5/24/rails-migrations-for-large-text-columns :
create_table :foo do |t|
...
t.text :new_col, :limit => 64.kilobytes + 1
...
end
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Leave a Comment
mysql text类型 长度不够的问题
2006-05-27 作者:amao 同分类文章
description:
转一篇文章存入数据库只能显示全面一部分，
ALTER TABLE fib_blog CHANGE content content LONGTEXT NOT NULL
修改数据库，然后看看 .htaccess使用指南 利用这个来让blog静态化。就像bbs.chinahtml测试数据一样
1.1 Migrations are Classes
A migration is a subclass of ActiveRecord::Migration that implements two class methods: up (perform the required transformations) and down (revert them).
Active Record provides methods that perform common data definition tasks in a database independent way (you’ll read about them in detail later):
create_table change_table drop_table add_column change_column rename_column remove_column add_index remove_index
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i found mysql text type has 64k limit,and for my application,it's not enough,so how to migrate from text to mediumtext,also i want keep my original data well
mysql text types schema alert
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alter table foo modify column bar mediumtext ;
change_column :urls,:content,:text,:limit=>128.kilobytes
change_column(table_name, column_name, type, options) : Changes the column to a different type using the same parameters as add_column.
http://api.rubyonrails.org/classes/ActiveRecord/Migration.html
http://guides.rubyonrails.org/migrations.html
ActiveRecord::Migration.upgrade_table :subtitles do |t|
t.integer :video_id, :null => false
end
这个方法写在rake里，以后就不用migration了，要不然文件太多了，是朋友教我的，呵呵
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