别名列的不同方法 [英] Different ways to alias a column

问题描述

 从雇员
 中选择empName作为EmployeeName有什么区别？ / pre> 
 
 
与
 从雇员$ b中选择EmployeeName = empName从技术角度来看，$ b  
。不知道这是否只是SQL Server专用。
 
 
 
欣赏您的答案。
解决方案
我希望使用第一个，因为第二个不是可移植的-
  select EmployeeName = empName来自员工的
  
是语法错误（至少在SQLite和Oracle中），或者可能不会您所期望的（比较两列EmployeeName和empName并以布尔值/整数返回比较结果），而
 选择empName雇员的EmployeeName 
  
与
 
 
 <$相同p $ p> 从雇员
中选择empName作为EmployeeName 
  

这是我的首选

What is the difference between

select  empName as EmployeeName from employees

versus

select  EmployeeName = empName from employees

from a technical point of view. Not sure if this is just SQL server specific or not.

Appreciate your answers.

解决方案

I'd prefer the first one, since the second one is not portable -

select  EmployeeName = empName from employees

is either a syntax error (at least in SQLite and Oracle), or it might not give you what you expect (comparing two columns EmployeeName and empName and returning the comparison result as a boolean/integer), whereas

select  empName EmployeeName from employees

is the same as

  select  empName as EmployeeName from employees

which is my preferred variant.

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