SQL SUBSTRING 与 RIGHT - 最佳实践 [英] SQL SUBSTRING vs RIGHT - Best Practice

问题描述

我试图找出从字符串开头删除字符时的最佳做法.

I'm trying to find out the best practice when removing characters from the start of a string.

在某些语言中，您可以使用不带长度参数的 MID，但在 TSQL 中需要长度.

In some languages, you can use MID without a length parameter however, in TSQL the length is required.

考虑以下代码，最佳实践是什么?(十六进制字符串是可变长度的)

Considering the following code, what is the best practise? (The hex string is variable length)

DECLARE @sHex VARCHAR(66)
SET @sHex = '0x7E260F3DA734AD4BD816B88F485CE501D843DF067C8EDCB8AC7DAD331852E04D'

PRINT RIGHT(@sHex,LEN(@sHex) -2)
PRINT SUBSTRING(@sHex,3,LEN(@sHex) -2)
PRINT SUBSTRING(@sHex,3,65535)

推荐答案

嗯，第一个更能表达您的意图.最后一个显然是混乱的(硬编码长度等).我怀疑你会发现第一个 & 之间有很大的性能差异.第二，所以我会使用最简单的 - RIGHT.

Well, the first is more expressive of your intent. The last is clearly messy (hard-coded length etc). I doubt you'd find much performance difference between the first & second, so I'd use the simplest - RIGHT.

当然，如果你做了这么多，你可以写一个 udf 来封装这个——那么如果你改变主意，你只有一个地方可以改变......

Of course, if you are doing this lots, you could write a udf that encapsulates this - then if you change your mind you only have one place to change...

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