On “Bad Habits to Kick : Using AS instead of = for column aliases” (via: Aaron Bertrand)

A while ago, I came across an interesting post Bad Habits to Kick : Using AS instead of = for column aliases by Aaron Bertrand, a major contributor on SQLblog.com – The SQL Server blog spot on the web.

The last link indicates my problem with this “AS” versus “=”: it is SQL Server specific.

So, if you mainly use SQL Server, then it is OK (or even preferable) to use “=” for aliasing columns in human written SQL as it makes spotting the names used much easier.

= alias

select
  tableName = o.name,
  columnName = c.name,
  columnTypeName = t.name
from sysobjects as o
inner join syscolumns as c on c.id = o.id
inner join systypes as t on t.usertype = c.usertype
where o.type = 'S'

as alias

select
  o.name as tableName,
  c.name as columnName,
  t.name as columnTypeName
from sysobjects as o
inner join syscolumns as c on c.id = o.id
inner join systypes as t on t.usertype = c.usertype
where o.type = 'S'

But if you regularly use othter DBMS, then you should use the classic AS alias.

DBSMS that only support AS alias

At least these do not support the = way of specifying an alias:

• Oracle SELECT.
• DB/2 subselect.
• Firebird.
• InterBase.

–jeroen

via: Aaron Bertrand : Bad Habits to Kick : Using AS instead of = for column aliases.