当我运行这个查询时，它显示从a，B和c开始first_name但是没有显示first_name从D开始为什么... [英] When I run this query, it's showing start first_name from a, B and c...but not showing first_name start from D why...

问题描述

when I run this query, it's showing start First_Name from A,B and C...but not showing First_Name start from D why...

我尝试过：

What I have tried:

select * from Employee where First_Name between 'A' and 'D' 

推荐答案

引用：

当我运行这个查询时，它显示从a，B和c开始first_name但是没有显示first_name从D开始为什么...

When I run this query, it's showing start first_name from a, B and c...but not showing first_name start from D why...

因为' D anuthing'> 'D'

尝试

Because 'D anuthing' > 'D'
Try

select * from Employee where First_Name between 'A' and 'E'

因为它正在使用字符串比较。

当你比较字符串时，它们会逐个字符地进行比较，整个比较的结果来自一对中的第一个差异。

因此，当你将'A'与'Andrew'进行比较时，'A '较低，因为第一个区别是'A'在'Andrew'之前结束。当你到达'D'时，会发生同样的事情：'D'出现在以D开头的任何字符串之前。由于BETWEEN指定序列的结尾，因此没有以D开头但具有多个字母的名称将在该范围内。

使用SUBSTRING提取第一个字符，或使用' E'作为上限并添加一个特定的检查以消除只是'E'的名称

Because it's using string comparisons.
When you compare strings, they are compared character by character, and the result of the whole comparison comes from the first difference in a pair.
So when you compare 'A' with 'Andrew', 'A' is lower, because the first difference is that 'A' ends before 'Andrew'. When you get to 'D', the same thing happens: 'D' comes before any string starting with a "D". Since BETWEEN specifies the end of the sequence, no name that starts with a "D" but has more than one letter will be in the range.
Either use SUBSTRING to extract the first character, or use 'E' as the upper limit and add a specific check to eliminate names which are just 'E'

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