SQL:Bit 或 char(1) 哪个更好 [英] SQL: What is better a Bit or a char(1)

问题描述

检索 bit 或 char(1) 是否有任何性能差异?

Is there any performance difference on retrieving a bit or a char(1) ?

出于好奇=]

更新:假设我使用的是 SQL Server 2008！

UPDATE: Suposing i'm using SQL Server 2008!

推荐答案

对于 SQL Server:一个字节内最多可以存储 8 列 BIT 类型的列，而 类型的每一列>CHAR(1) 将占用一个字节.

For SQL Server: up to 8 columns of type BIT can be stored inside a single byte, while each column of type CHAR(1) will take up one byte.

另一方面:BIT 列可以有两个值(0 = false，1 = true)或根本没有值 (NULL) - 而 CHAR(1) 可以有任何字符值(更多的可能性)

On the other hand: a BIT column can have two values (0 = false, 1 = true) or no value at all (NULL) - while a CHAR(1) can have any character value (much more possibilities)

实际上，归结为:

• 您真的需要真/假(是/否)字段吗?如果是这样:使用 BIT
• 您是否需要具有两个以上可能值的东西 - 使用 CHAR(1)

从性能的角度来看，我认为这没有任何显着差异 - 除非您有数万列.那么当然，使用 BIT 可以在单个字节中存储多达 8 列将是有益的.但同样:对于您的普通"数据库案例，您有几列，一打这样的列，这真的没有太大区别.选择适合您需求的列类型 - 不要过度担心性能.....

I don't think it makes any significant difference, from a performance point of view - unless you have tens of thousands of columns. Then of course, using BIT which can store up to 8 columns in a single byte would be beneficial. But again: for your "normal" database case, where you have a few, a dozen of those columns, it really doesn't make a big difference. Pick the column type that suits your needs - don't over-worry about performance.....

这篇关于SQL:Bit 或 char(1) 哪个更好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！