什么是asp.net会员表降下*列的点？ [英] What is the point of the Lowered* columns in asp.net membership tables?

问题描述

什么是用在ASP.Net成员和朋友的SQL模式低pfixed列名$ P $建筑原因是什么？有问题的列的一些例子是如下：

What is the architectural reason for the column names prefixed with "Lowered" in the SQL schema for ASP.Net membership and friends? Some examples of the columns in question are below:

• aspnet_Applications.LoweredApplicationName


• aspnet_users.LoweredUserName


• aspnet_membership.LowerEmail

我看到降低列索引，但在我看来，你可以只指数相关的非降低柱离开了明显的重复。

I see that the lowered columns are indexed, but it seems to me that you could just index the associated non-lowered column and leave out the apparent duplication.

我敢肯定有一个很好的理由为他们的存在，但我不明白。

I'm sure there is a good reason for them to exist, but I can't figure it out.

推荐答案

有在如SQL Server非区分大小写的数据库没有目的这一点。这是一个可重用的数据库，无论在哪个您所使用的数据库的类型。例如。 Informix的是区分大小写为其存储的所有字符串数据。一个Informix服务器上使用这个数据库将是一个很好的理由，/使用此列，而不是较低的（）'ING自己的列。我不是说你不能以任何方式（VARBINARY，BINARY_CHECKSUM，运行时间/声明整理，等）做区分大小写的搜索在SQL Server中。这将改变开箱数据库的功能。

There is no purpose for this in a non case sensitive database like SQL Server. This is a reusable database regardless of the type of database in which you are using. E.g. Informix is case-sensitive for all string data which is stored. Using this database on an Informix server would be a good reason to have/use this column instead of lower()'ing the column yourself. I am not saying that you can't do case sensitive searches in SQL Server by any means (varbinary, BINARY_CHECKSUM, runtime/declarative COLLATE, etc.). This would change the functionality of the out of the box database.

任何计算的列的想法是，以节省在查询期间做这些计算周期。最特别是在大型查询。另一个想法是其中一个你索引的列了。再次，这样做是为了节省周期。

The idea of any calculated column is to save cycles on doing those calculations during querying. Most especially during large queries. The other thought is one which you had in indexing those columns. Again, this is done to save cycles.

这篇关于什么是asp.net会员表降下*列的点？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！