I am using MySQL,I have table called constructions where there is a column called phone, phone numbers are in format 9876543210 but I want to clean the column wherever there are alphabets and symbols.
I was using:
select * from constructions where phone like '[a-Z]%';
but this is wrong, i guess it works in SQL-Server.
No to SQL Server unless you add a regular expression utility function. You have the built in find replace functions but those are very simple.
For MySQL look to the reference manual here >>> http://dev.mysql.com/doc/refman/5.0/en/regexp.html
Instead of LIKE use the RLIKE version that works with regular expressions.
Related
This is the query I'm using but it's returning an empty table
select ename from new_schema.employee where ename like '[svg]%' ;
It looks like you're using Microsoft SQL Server syntax for the pattern.
MySQL only supports standard wildcards for the LIKE predicate. I.e. % and _, but not square brackets.
You can use a regular expression instead of LIKE to search for a character class:
select ename from new_schema.employee where ename REGEXP '^[svg].*' ;
You should keep in mind that every vendor of SQL database does things differently, and implements their own ideas about extensions to standard SQL. You need to refer to documentation for the brand and version you are using, and don't expect features that work in one brand (Microsoft) to work the same in another brand (MySQL).
I'am trying to write a SELECT-Statement to retrieve a list of Usernames from my Database. My Pattern is: /placeholder\d+/ig and I already tested it and can confirm it is working properly. I'am trying to retrieve every Placeholder in the Table.
I also tried to escape the \ after placeholder.
My SQL-Statement is: SELECT * FROM table WHERE (name REGEX '/placeholder\d+/ig') ... I tried different variations with backticks, etc or LIKE instead of REGEXbut LIKEonly has % and _ as a Wildcard.
Does my RegEx pattern needs to be modified in order to work with MySQL?
Unlike most scripting languages, MySQL is not using the PREG library for regular expression matching.
So yes, you need to modify your regex to make it work properly in MySQL:
SELECT * FROM table WHERE name REGEXP 'placeholder[0-9]+'
OR
SELECT * FROM table WHERE name REGEXP 'placeholder[[:digit:]]+'
There are no short-hand character classes like \d in MySQL. Also, you do not use the regex-delimeter ("/../si" is just ".." in MySQL)
Read the documentation on regular expressions in MySQL for more information.
I have the following query:
SELECT item from table
Which gives me:
<title>Titanic</title>
How would I extract the name "Titanic" from this? Something like:
SELECT re.find('\>(.+)\>, item) FROM table
What would be the correct syntax for this?
By default, MySQL does not provide functionality for extracting text using regular expressions. You can use REGEXP to find rows that match something like >.+<, but there is no straightforward way of extracting the captured group without some additional effort, such as:
using a library like lib_mysqludf_preg
writing your own MySQL function to extract matched text
performing regular string manipulation
using the regex functionality of whatever environment you're using MySQL from (e.g. PHP's preg_match)
reconsidering your need for regular expressions entirely. If you know that all your rows contain a <title> tag, for instance, it may be a better idea to simply use "normal" string functions such as SUBSTRING
As pointed out in the informative answer by George Bahij MySQL lacks this functionality so the options would be to either extend the functionality using udfs etc, or use the available string functions, in which case you could do:
SELECT
SUBSTR(
SUBSTRING_INDEX(
SUBSTRING_INDEX(item,'<title>',2)
,'</title>',1)
FROM 8
)
from table
Or if the string you need to extract from always is on the format <title>item</title> then you could simple use replace: replace(replace(item, '<title>', ''), '</title>','')
This regex: <\w+>.+</\w+> will match content in tags.
Your query should be something like:
SELECT * FROM `table` WHERE `field` REGEXP '<\w+>.+</\w+>';
Then if you're using PHP or something similar you could use a function like strip_tags to extract the content between the tags.
XML shouldn't be parsed with regexes, and at any rate MySQL only supports matching, not replacement.
But MySQL supports XPath 1.0. You should be able to simply do this:
SELECT ExtractValue(item,'/title') AS item_title FROM table;
https://dev.mysql.com/doc/refman/5.6/en/xml-functions.html
In field post_content I have a string like this in nearly 800 rows:
http://somesite.com/">This is some site</a>
I need to remove everything from "> onwards so that it leaves just the URL. I can't do a straight find and replace because the text is unique.
Any clues? This is really my first foray into MySQL database modifications but I did do an extensive search before posting here.
Thanks,
~Kyle~
From this site: http://www.regular-expressions.info/mysql.html
LIB_MYSQLUDF_PREG
If you want more regular expression power in your database, you can consider using LIB_MYSQLUDF_PREG. This is an open source library of MySQL user functions that imports the PCRE library. LIB_MYSQLUDF_PREG is delivered in source code form only. To use it, you'll need to be able to compile it and install it into your MySQL server. Installing this library does not change MySQL's built-in regex support in any way. It merely makes the following additional functions available:
Here it comes...
PREG_CAPTURE extracts a regex match from a string. PREG_POSITION returns the position at which a regular expression matches a string. PREG_REPLACE performs a search-and-replace on a string. PREG_RLIKE tests whether a regex matches a string.
Sounds exactly what you're looking for.
All these functions take a regular expression as their first parameter. This regular expression must be formatted like a Perl regular expression operator. E.g. to test if regex matches the subject case insensitively, you'd use the MySQL code PREG_RLIKE('/regex/i', subject). This is similar to PHP's preg functions, which also require the extra // delimiters for regular expressions inside the PHP string.
See this post: How to do a regular expression replace in MySQL?
Either that or you could just write a script in any lanugage which goes through each record, does a regex replacement and then updates the field. For more info on regex, see here: http://www.regular-expressions.info/reference.html
There's a number of options. One might be to use SUBSTRING_INDEX():
UPDATE
table
SET field = SUBSTRING_INDEX( field, '">', 1 )
It's possible - there is a syntax for User Defined Functions which would let you pass in a regular expression pattern that matches the link and strips everything else.
However, this is quite complicated for somebody new to MySQL, and from your question, this sounds like a one-off. In which case - why not just use Excel and then reimport the data?
Great stuff!
All seems doable with a little bit of time and self education.
In the end, I exported that table as a CSV in Sequel Pro and did some nifty find and replace work in Coda. Not as sophisticated as your suggestions, but it worked.
Thanks again,
~Kyle~
I'm using sqlite3 to try and find users who have an e-mail address that is either with Gmail, Yahoo or Hotmail. It needs to do this just on the basis of the first part of the domain, so I want any address that had the #yahoo to be accepted.
It appears from documentation that it is not possible to use a regular expression when querying an sqlite database. Is there any elegant way of doing something similar? It doesn't seem to be possible to use a "like/in" with multiple options (eg: LIKE (%#yahoo%, %#gmail%, %#hotmail%)?
Failing that, I may switch over to MySQL for a reg exp as I want to keep the solution simple and elegant and DB isn't a major factor. How would said regexp query be written in MySQL?
You can't use multiple "LIKE" in that way but you can use:
(email LIKE "%#yahoo%" OR email LIKE "%#gmail%" OR ....)
you can use the way Nemoden is using or something like this (not tested)
WHERE email REGEXP '[\w\.]+#(yahoo|gmail|ymail|hotmail)\.(com|ru|co\.uk)'
This would be much faster because LIKE %string% OR ... is very slow and doesnt use any indexes(dont know if REGEXP uses indexes tho).
I think you might want something like this (RLIKE function):
WHERE email RLIKE '^[A-Z0-9._%+-]+#[A-Z0-9.-]+\.([A-Z]{2}|com|org|net|edu|gov|mil|biz|info|mobi|name|aero|asia|jobs|museum|travel)$'
If you use whatever_cs (case sensitive collation), use a-zA-Z instead of A-Z.
You can also get rid of ^ and $ in the regex. ^ means "starts with" and $ means "ends with"
UPDATE:
'.*#(gmail|hotmail|yahoo)\.[A-Z]{2,4}'