Mysql自增id是什么


mysql

自增ID

select last_insert_id()

自增ID独一无二

The ID that was generated is maintained in the server on a per-connection basis. This means that the value returned by the function to a given client is the first AUTO_INCREMENT value generated for most recent statement affecting an AUTO_INCREMENT column by that client. This value cannot be affected by other clients, even if they generate AUTO_INCREMENT values of their own. This behavior ensures that each client can retrieve its own ID without concern for the activity of other clients, and without the need for locks or transactions. —— Mysql5.6 官方文档

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段子和笑话


笑话

北极熊

忘记带钥匙

有一天北极熊出门忘记带钥匙了
“然后呢”
“然后它冷死了”

为什么北极熊不吃企鹅

“为什么北极熊从来不吃企鹅🐧”
“因为北上时经过了广东省”

自恋

黄婆卖瓜

Dear 乔鑫
你的英俊潇洒，威武神勇，聪明伶俐
让我着迷
我痴迷于你的破案手段
我想在你的臂弯里度过晚年
By 乔鑫

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jdk源码阅读--不持续更新


jdk

SPI机制

From Java documentation:
A service is a well-known set of interfaces and (usually abstract) classes. A service provider is a specific implementation of a service. The classes in a provider typically implement the interfaces and subclass the classes defined in the service itself. Service providers can be installed in an implementation of the Java platform in the form of extensions, that is, jar files placed into any of the usual extension directories. Providers can also be made available by adding them to the application’s class path or by some other platform-specific means—–By wiki
大致意思为：服务提供者是服务的特定实现。提供程序中的类通常实现接口，并子类化服务本身中定义的类。服务提供程序可以扩展的形式安装在Java平台的实现中，也就是说，将jar文件放置在任何常用扩展目录中。也可以通过将提供者添加到应用程序的类路径或通过其他一些特定于平台的方式来使提供者可用。

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