sql - Strip last two characters of a column in MySQL

Question

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.

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.

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

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

Answer 1

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

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.php.php becomes index (!)
-- index.txt remains index.txt