何时使用“=”与 "as" 引入别名以及该版本的名称是什么

Question

什么时候 sql 的 flavor 名称支持“=”作为别名而不是使用“as”？

SELECT 
 A = Col1
,B = Col2
FROM Table

相对于SQL-86

SELECT
  Col1 AS A
, Col2 AS B
FROM Table

Answer 1

这让我感到非常惊讶。 column_alias = 表达式似乎一直是 T-SQL.

原始语法的一部分

已将 AS 命令添加到 T-SQL.80 (2000) 以与 SQL-92 兼容。

SQL2000_release.pdf 第 1459 页的摘录

The AS clause is the syntax defined in the SQL-92 standard for assigning a name to a result set column. This is the preferred
syntax to use in Microsoft® SQL Server™.

column_name AS column_alias

Or

result_column_expression AS derived_column_name

Transact-SQL also supports the following syntax for compatibility with earlier versions of SQL Server:

column_alias = column_name

何时使用“=”与 "as" 引入别名以及该版本的名称是什么

When was aliasing using "=" versus "as" introduced and what is the name of that version

sql-server

ansi-sql

column-alias