chengzq11

TA的文章
  • C# func and action委托是什么?
    1) 回答这个问题之前,我们需要了解什么是委托(英文 Delegate )? 为了便于理解,再往前推一步,回到c语言时代,指针的概念。 什么是指针,其实就是内存地址。 那什么是内存地址?就要先说说内存条了,通常情况下我们在网上买的内存条比如8G,16G, 这个是硬件设备。 那内存条8G和16G的含义是什么? 就涉及内存的另外两个概念: 1.内存的寻址能力。 即每个内存单位能存多少位(bit), 每一个bit,其实就是存放0或者1。 内存寻址能力通常是8位,单位是字节,8bit=1byte。 2.内存的地址范围,专业点叫寻址空间。 8G内存条能存放的数据量: 1(Byte)*2^10(KB)*2...
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    •  2020-10-13
  • 一道sql 列转行的实现
    在Sql Sever下,可以使用With AS构造数据,使用Pivot实现转换, 具体sql如下: ---构造测试数据 With test as ( Select 1991 as [year], 1 as [month], 1.1 as [amount] union all Select 1991 as [year], 2 as [month], 1.2 as [amount] union all Select 1991 as [year], 3 as [month], 1.3 as [amount] union all Select 1991 as [year], 4 as [month],...
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    •  2020-10-13
  • Understanding A/B Testing
    Understanding A/B Testing A/B testing is the process of testing two elements to determine which performs more effectively. Use correctly, it can help your organization identify value-added activities with data you already have. Allowing you to capitalize on opportunities quickly. With customer data ...
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    •  2020-07-20