SQL 基本的函数

select * from emp; <img 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" alt="" /> select max(sal) from emp;--sal中最大值 <img src="data:image/png;base64,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" alt="" /> select min(sal)…

UE4中使用数据表(Data Table)

本文依据官方文档数据驱动游戏性元素整理而来。 做过游戏的应该都清楚,如果游戏稍微有点规模,那么使用数据驱动来做游戏一般是必不可少的一步,一般也就是策划通过本表的方式来解决。下面我们来简单说一下UE4中如何使用DataTable来实现数据驱动开发。 顾名思义,数据表就是以有意义且有用的方式将各种相关的数据归类的表格, 其中,数据字段可以是任何有效的 UObject 属性,包括资产引用。在设计师将 CSV 文件导入数据表前,程序员必须创建行容器以指示引擎如何解释数据。 这些数据表包含了列名,这些列名和基于代码的UStruct结构以及它的(子)变量一一对应, 这个UStruct的结构必须继承自FTableRowBase才可以被导入器辨识。 我们随便建了一张测试表(csv)如下所示: Id,HP,Icon,BlueprintKey 1,100,Texture2D’/Game/FirstPerson/Textures/Test.Test’,Class’/Game/FirstPerson/BP_DataTableTest.BP_DataTableTest_C’ 2,200,Texture2D’/Game/FirstPerson/Textures/Test.Test’,Class’/Game/FirstPerson/BP_DataTableTest.BP_DataTableTest_C’ 其中BP_DataTableTest是一个继承自AActor的一个蓝图类,BP_DataTableTest_C是实际生成的蓝图类。 对应的C++代码如下所示: /** 注意此结构体中的成员变量的名字要跟csv表中的相同,因为它是UE4里面是通过反射系统来实现数据的初始化的,当然名字不同也可以,但是它的元数据中的DisplayName就必须跟表中的字段值对应,具体可以参考DataTableCSV.cpp中的实现就可以了解。*/USTRUCT(BlueprintType)struct…