I have a series of mysql scripts that run from a shell script. One of the queries includes
Select * from Table where FieldX Regex 'XYZ$'
in other words 'ends with XYZ'. However this is breaking the script. If I remove the $ or make it literal \$ it works but neither serves my purpose. Is there an altnerative character I can use that Regexp will understand as 'end of line' and Shell Script won't object to?
Since you're using single quotes to delimit the shell string, you need to use double quotes to delimit MySQL strings inside it.
'and FieldX Regex "XYZ$"
Related
This failed in Java 13 (JDBC) code so I went to MySQL Workbench to duplicate problem.
I run a simple query as:
START TRANSACTION;
SET SESSION sql_mode = NO_BACKSLASH_ESCAPES;
SELECT *, "x\\x", "y\y" from dirs
WHERE d_pathname like 'E:\\\\BOOKS\\\\Dictionaries_and_Encyclopedias\\\\%' ORDER BY d_pathname;
and I get 400 rows returned. The issue is, that I do not want to use double-backslashes.
Rows returned show a single backslash, not a double backslash.
Interestingly, the x\\x and y\y clauses appear just as represented in the SELECT statement.
When I remove the double backslashes in the LIKE clause, I get zero rows!
Why? I'd rather not have to double-up the backslashes, and run simple and clean code.
The NO_BACKSLASH_ESCAPES mode only affects how backslashes are treated in ordinary string literals. It doesn't change how they're processed in LIKE patterns.
However, you can use the ESCAPE option to specify a different character to use as the escape character in LIKE. Just use some other character that doesn't appear in your pattern.
WHERE d_pathname like 'E:\BOOKS\Dictionaries_and_Encyclopedias\%' ESCAPE '|'
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
So I am building a database of all my text messages to get information about my habits and I'm having trouble importing the contents of the messages. Whenever there are apostrophes (often) or quotation marks (not as rare as you might think), I get syntax issues.
Is there a way to make MySQL use something other than " or ' to encase strings (specifically, the field is a VARCHAR). If I could use a ~ or some other rarely used character in text messaging my life would become a whole lot easier.
Preferably you should use parameterised queries, then your database connector takes care of sending the strings to the database in the correct way.
If you need to build the queries by concatenating the values into a query, you need to escape the strings correctly to make them string literals in the SQL code.
Stick to one delimiter for strings, don't use apostrophes around some strings and qoutation marks around others, that only makes it harder to escape them correctly. I suggest that you use apostrophes, as that is what the SQL standard specifies.
To escape the strings correctly to be a string literal delimited by apostropes, you should:
Replace all backslashes by double backslashes, then
Replace all apostrophes by a backslash and an apostrophe
For example, to make the string It's an "example" with a backslash(\). into a string literal, it should end up like this in a query:
insert into Table (txt) values ('It\'s an "example" with a backslash(\\).')
Note: This is a correct way to escape strings for MySQL. Other databases may use different characters for escaping and need other characters to be escaped, so using this for any other database may fail, or even worse open up for SQL injection attacks.
I'm working in development mode with an H2 in memory database, but I'd like it to behave as much as possible like a mysql database (see http://www.h2database.com/html/features.html#compatibility)
this is my configuration in application.conf file:
db.default.driver=org.h2.Driver
db.default.url="jdbc:h2:mem:play;MODE=MYSQL;DB_CLOSE_DELAY=-1"
to test it I just run "play" and from play's console I issue "h2-browser" and in the url jdbc field I enter "jdbc:h2:mem:play;MODE=MYSQL;DB_CLOSE_DELAY=-1"
the following statements work ok in mysql:
CREATE TABLE `tmp` (
`name` varchar(50) NOT NULL
);
insert into tmp (name) values ('slash: \\, simple quotes \', double quotes \" -');
select * from tmp;
but in the h2 console I get an error, and the only character I can escape is the single quotes, just by preceding it with another single quote. (Also tried entering 'SET MODE MySQL;')
Is there some way to have h2 behave like mysql from play's framework h2-browser? or is it just a limitation of h2?
The link you provided, http://www.h2database.com/html/features.html#compatibility, documents the exact compatibility features H2 supports. Things that are not documented are not supported. In this case it seems the problem is the 'backslash' escaping within a String literal:
'slash: \\, simple quotes \', double quotes \" -'
The backslash is not an escape character for ANSI SQL; to escape a single quote you need to use two single quotes. The problem is this might not work for MySQL as the single backslash is still an escape character:
'slash: \, simple quotes '', double quotes " -'
For this problem, a solution is to use the ANSI mode for MySQL, another solution is to always use bind variables for String literals (PreparedStatement within JDBC).
Attempting to change the "files" folder location in a Drupal site from /files to /sites/default/files.
In order to avoid changing anything else such as
http://www.google.com/profiles/
I'm trying to use a basic regular expression with a word boundary.
\bfiles/
A quick check in regexpal is working as expected, but when I enter the above in the phpMyAdmin search , checking the "as regular expression" checkbox, I don't get the expected result.
Two questions:
How should I write my expression with a word boundary so that it works in phpMyAdmin?
I'm really a newbie at SQL statements! Would it be possible to write a SQL query that would simply look for every occurrence of "files/" & replace it with "sites/default/files/"?
According to the MySql docs, the regex flavour used is POSIX 1003.2. For this flavour of regex, word boundaries are as follows:
[[:<:]] (beginning) [[:>:]] (end)
so your regex would be:
[[:<:]]files/
If you want to use sql to search and replace all instances of [[:<:]]files/ from a specific field in a table, you could use a UDF such as the one found here
Also, you should be aware of the following while using regex with MySql:
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.