I tried running this query:
SELECT column FROM table WHERE column REGEXP '[^A-Za-z\-\']'
but this returns
#1139 - Got error 'invalid character range' from regexp
which seems to me like the - in the character class is not being escaped, and instead read as an invalid range. Is there some other way that it's suppose to be escaped for mysql to be the literal -?
This regex works as expected outside of mysql, https://regex101.com/r/wE8vY5/1.
I came up with an alternative to that regex which is
SELECT column FROM table WHERE column NOT REGEXP '([:alpha:]|-|\')'
so the question isn't how do I get this to work. The question is why doesn't the first regex work?
Here's a SQL fiddle of the issue, http://sqlfiddle.com/#!9/f8a006/1.
Also, there is no language being used here, query is being run at DB level.
Regex in PHP: http://sandbox.onlinephpfunctions.com/code/10f5fe2939bdbbbebcc986c171a97c0d63d06e55
Regex in JS: https://jsfiddle.net/6ay4zmrb/
Just change the order.
SELECT column FROM table WHERE column REGEXP '[^-A-Za-z\']'
#Avinash Raj is correct the - must be first (or last). The \ is not an escape character in POSIX, which is what mysql uses, https://dev.mysql.com/doc/refman/5.1/en/regexp.html.
One key syntactic difference is that the backslash is NOT a metacharacter in a POSIX bracket expression.
-http://www.regular-expressions.info/posixbrackets.html
What special characters must be escaped in regular expressions?
Inside character classes, the backslash is a literal character in POSIX regular expressions. You cannot use it to escape anything. You have to use "clever placement" if you want to include character class metacharacters as literals. Put the ^ anywhere except at the start, the ] at the start, and the - at the start or the end of the character class to match these literally
Related
This question already has answers here:
How should I escape characters inside this LIKE query?
(4 answers)
Closed last year.
I have a column called \'column. I am able to use it in SELECT statements just like any other column. However, when I try to perform SHOW COLUMNS FROM myTable LIKE '\\''column' I get no results. I observed that it works if I double escape the backslash: '\\\\''column'.
I tested this from MariaDB console, but I also observed the same behaviour in MySQL 8.
How does the escaping work? How should I properly escape the value so that I can fetch the column information?
DB Fiddle
From the mysql documentation
MySQL uses C escape syntax in strings (for example, \n to represent
the newline character). If you want a LIKE string to contain a literal
, you must double it. (Unless the NO_BACKSLASH_ESCAPES SQL mode is
enabled, in which case no escape character is used.) For example, to
search for \n, specify it as \\n. To search for \, specify it as \\\\;
this is because the backslashes are stripped once by the parser and
again when the pattern match is made, leaving a single backslash to be
matched against.
I have written regex and tested it online, works fine. When I test in terminal, MySQL console, it doesn't match and I get an empty set. I believe MySQL regexp syntax is somehow different but I cannot find the right way.
This is data I use:
edu.ba;
medu.ba;
edu.ba;
med.edu.ba;
edu.com;
edu.ba
I should get only edu.ba matches including; if there is some. Works fine except in actual query.
(\;+|^)\bedu.ba\b(\;+|$|\n)
Is there anything I could change to get the same results?
You want to match edu.ba in between semi-colons or start/end of string. The word boundaries are redundant here (although if you want to experiment, the MySQL regex before MySQL v8 used [[:<:]] / [[:>:]] word boundaries, and in MySQL v8+, you need to use double backslashes with \b - '\\b').
Use
(;|^)edu[.]ba(;|$)
Details
(;|^) - ; or start of string
edu[.]ba - edu.ba literal string (dot inside brackets always matches a literal dot)
(;|$) - ; or end of string.
I'm attempting to replicate the following regex pattern in a MySql query: http://regexr.com/3gt57
I'm unable to use a like as I need to match words that begin with the submitted term but don't necessarily contain the term.
I can't seem to use the pattern in a REGEXP query:
SELECT * FROM serialised_post
WHERE post_content REGEXP '\bSugg\S*';
Any help would be appreciated
In MySQL regexp, \S = [^[:space:]] (a negated bracket expression matching any char other than a whitespace char ([:space:] is a POSIX character class matching any whitespace)) and \b (here, a leading word boundary) is [[:<:]].
Use
WHERE post_content REGEXP '[[:<:]]Sugg[^[:space:]]*';
See more details about MySQL regex syntax here.
I'm using regex to find specific search but the last separator getting ignore.
Must search for |49213[A-Z]| but searches for |49213[A-Z]
SELECT * FROM table WHERE (data REGEXP '/\|49213[A-Z]+\|/')
Why are you using | in the pattern? Why the +?
SELECT * FROM table WHERE (data REGEXP '\|49213[A-Z]\|')
If you want multiple:
SELECT * FROM table WHERE (data REGEXP '\|49213[A-Z]+\|')
or:
SELECT * FROM table WHERE (data REGEXP '[|]49213[A-Z][|]')
Aha. That is rather subtle.
\ escapes certain characters that have special meaning.
But it does not seem to do so for | ("or") or . ("any byte"), etc.
So, \| is the same as |.
But the regexp parser does not like having either side of "or" being empty. (I suspect this is a "bug"). Hence the error message.
https://dev.mysql.com/doc/refman/5.7/en/regexp.html says
To use a literal instance of a special character in a regular expression, precede it by two backslash () characters. The MySQL parser interprets one of the backslashes, and the regular expression library interprets the other. For example, to match the string 1+2 that contains the special + character, only the last of the following regular expressions is the correct one:
The best fix seems to be [|] or \\| instead of \| when you want the pipe character.
Someday, the REGEXP parser in MySQL will be upgraded to PCRE as in MariaDB. Then a lot more features will come, and this 'bug' may go away.
Consider the following regex
#(.*\..*){2,}
Expected behaviour:
a#b doesnt match
a#b.c doesnt match
a#b.c.d matches
a#b.c.d.e matches
and so on
Testing in regexpal it works as expected.
Using it it in a mysql select doesn't work as expected. Query:
SELECT * FROM `users` where mail regexp '#(.*\..*){2,}'
is returning lines like
foo#example.com
that should not match the given regex. Why?
I think the answer to your question is here.
Because MySQL uses the C escape syntax in strings (for example, “\n”
to represent the newline character), you must double any “\” that you
use in your REGEXP strings.
MYSQL Reference
Because your middle dot wasn't properly escaped it was treated as just another wildcard and in the end your expression was effectively collapsed to #.{2,} or #..+
#anubhava's answer is probably a better substitute for what you tried to do though I would note #dasblinkenlight's comment about using the character class [.] which will make it easy to drop in a regex you've already tested in at RegexPal.
You can use:
SELECT * FROM `users` where mail REGEXP '([^.]*\\.){2}'
to enforce at least 2 dots in mail column.
I would match two dots in MySQL using like:
where col like '%#.%.%'
The problem with your code is that .* (match-everything dot) matches dot '.' character. Replacing it with [^.]* fixes the problem:
SELECT *
FROM `users`
where mail regexp '#([^.]*[.]){2,}'
Note the use of [.] in place of the equivalent \.. This syntax makes it easier to embed the regex into programming languages that use backslash as escape character in their string literals.
Demo.