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Difference between Select Unique and Select Distinct
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SELECT UNIQUE is old syntax supported by Oracle's flavor of SQL. It is synonymous with SELECT DISTINCT.
Use SELECT DISTINCT because this is standard SQL, and SELECT UNIQUE is non-standard, and in database brands other than ...
Kill a postgresql session/connection
...user to use this function. This works on all operating systems the same.
SELECT
pg_terminate_backend(pid)
FROM
pg_stat_activity
WHERE
-- don't kill my own connection!
pid <> pg_backend_pid()
-- don't kill the connections to other databases
AND datname = 'database...
UnicodeEncodeError: 'latin-1' codec can't encode character
...t. They map exactly to the Unicode characters U+0080–U+009F, which are a selection of control characters. They're control characters that aren't used very much which is why browsers got away with it, but it's annoying when you are trying to convert a sequences of bytes-as-Unicode.
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Create a new Ruby on Rails application using MySQL instead of SQLite
I want to create my Rails application with MySQL, because I like it so much. How can I do that in the latest version of Rails instead of the default SQLite?
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Remove Identity from a column in a table
...USTERED INDEX IX_Original_Value ON Original (Value);
INSERT INTO Original
SELECT 'abcd'
UNION ALL
SELECT 'defg';
You can do the following:
--create new table with no IDENTITY
CREATE TABLE Original2
(
Id INT PRIMARY KEY
, Value NVARCHAR(300)
);
CREATE NONCLUSTERED INDEX IX_Original_Value2 ON O...
搭建高可用mongodb集群（一）——配置mongodb - 大数据 & AI - 清泛网 - 专...
...东西，所以把自己实战的步骤记录下来以备忘。我们看看如何一步一步搭建这个东东。
一、mongodb单实例。这种配置只适合简易开发时使用，生产使用不行，因为单节点挂掉整个数据业务全挂，如下图。
虽然不能生产使用，...
linux 下巧妙使用squid代理服务器 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...控制类别很多，可以通过IP地址、主机名、MAC地址和用户/密码认证等识别用户，也可以通过域名、域后缀、文件类型、IP地址、端口和URL匹配等控制用户的访问，还可以使用时间区间对用户进行管理
-i选项：表示忽略列表值的...
【持续更新】App Inventor 2 中文拓展一览 - App Inventor 2 中文网 - 清泛...
... 专题
【FTP】App Inventor 2 FTP 上传下载全方案总结
【MD5、密码安全】Encrypt.Security 安全性扩展：MD5哈希，SHA1和SHA256哈希，AES加密/解密，RSA加密/解密，BASE64编码/解码
【AES加解密】MareshaAES 拓展：AES加解密算法
【二进制】UrsAI2Byt...
App Inventor接入Supabase：开源免费的后端新选择 - App Inventor 2 拓展 -...
...建项目
在Supabase控制台创建一个新的项目，设置数据库密码，等待项目初始化完成（通常需要2-3分钟）。
3. 获取配置参数
项目创建后，在项目设置的API页面获取：
- Supabase URL：你的项目专属API地址
- anon API Key：匿名公...
Python: How would you save a simple settings/config file?
...s')) # You know the datatype?
which outputs
List all contents
Section: mysql
x host:::localhost:::<type 'str'>
x user:::root:::<type 'str'>
x passwd:::my secret password:::<type 'str'>
x db:::write-math:::<type 'str'>
Section: other
x preprocessing_queue:::["preprocessing...