摘要：left join(左联接) 返回包括左表中的所有记录和右表中联结字段相等的记录right join(右联接) 返回包括右表中的所有记录和左表中联结字段相等的记录inner join(等值连接) 只返回两个表中联结字段相等的行举例如下： -------------------------------------------- 表A记录如下： aID aNum 1 a20050111 2 a20050112 3 a20050113 4 a20050114 5 a20050115 表B记录如下: bID bName 1 2006032401 2 2006032402 3 2006032403 4 阅读全文

摘要：Stored Procedures and triggers within a database are similar constructs. They can both perform the same SQL statements. The biggest difference between the two is how they are executed. A stored procedure has to be executed by a user, while a trigger is executed by the system as the result of an even 阅读全文

摘要：About SQLite: SQLite is an embedded SQL database engine. It reads and writes directly to disk files which contain all information about the database. The database file format is cross-platform-you can freely copy a database between 32-bit and 64-bit systems. SQLite is a compact library. With all fea 阅读全文

摘要：之前面试时被问及抽象类与接口的区别，感觉答得很不好，所以在此总结一下这个问题： 首先抽象类是一种特殊的类，它可以含有方法的定义和实现，也可以包含属性，构造函数等。当然抽象类也可以包含抽象函数和虚函数。 这个是C#三大特性之一多态的重要组成部分。 抽象类主要用于关系密切的对象之前，比如铁门和木门都是门，他们都继承自抽象类“门”。重点是“是什么？” 一个派生类只能继承至一个类（包括抽象类），派生类必须... 阅读全文