删除MySQL中列的最后两个字符 [英] Strip last two characters of a column in MySQL

问题描述

我有一个SQL列，其中的条目是字符串.我需要在剪掉最后两个字符后显示这些条目，例如如果条目为199902345，则应输出1999023.

I have an SQL column where the entries are strings. I need to display those entries after trimming the last two characters, e.g. if the entry is 199902345 it should output 1999023.

我尝试研究TRIM，但看起来只有在我们知道最后两个字符是什么的情况下，它才能提供修剪功能.但就我而言，我不知道最后两个数字是什么，只需要丢弃它们即可.

I tried looking into TRIM but looks like it offers to trim only if we know what are the last two characters. But in my case, I don't know what those last two numbers are and they just need to be discarded.

那么，简而言之，什么MySQL字符串操作可以修剪字符串的最后两个字符?

So, in short, what MySQL string operation enables to trim the last two characters of a string?

我必须补充一点，字符串的长度不是固定的.可以是9个字符，也可以是11个字符.

I must add that the length of the string is not fixed. It could be 9 characters, 11 characters or whatsoever.

推荐答案

要从字符串中选择除最后一个 n 以外的所有字符(或换句话说，删除最后一个 n >字符串中的字符)；使用 SUBSTRING 和 CHAR_LENGTH 一起起作用:

To select all characters except the last n from a string (or put another way, remove last n characters from a string); use the SUBSTRING and CHAR_LENGTH functions together:

SELECT col
     , /* ANSI Syntax  */ SUBSTRING(col FROM 1 FOR CHAR_LENGTH(col) - 2) AS col_trimmed
     , /* MySQL Syntax */ SUBSTRING(col,     1,    CHAR_LENGTH(col) - 2) AS col_trimmed
FROM tbl

要从字符串末尾删除特定的子字符串，请使用

To remove a specific substring from the end of string, use the TRIM function:

SELECT col
     , TRIM(TRAILING '.php' FROM col)
-- index.php becomes index
-- index.txt remains index.txt

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