Problem:
I want to get all records that contain a subdomain.
Some subdomains are saved prefixed with www. after the http://, but not all are.
Examples:
http://www.sub.domain.com and http://sub.domain.com
I have this working regex that I have tested on RegExr:
^(http:\/\/)(www\.)?(\w)+(\.)(\w)+(.)(\w|\/){2,10}
Which matches both examples nicely.
However when I try using this regex in my query using REGEXP, mysql returns 0 records.
I have tried:
SELECT * FROM `front` WHERE `domain` REGEXP '^(http:\/\/)(www\.)?(\w)+(\.)(\w)+(\.)(\w|\/){2,10}$';
SELECT * FROM `front` WHERE `domain` REGEXP '/^(http:\/\/)(www\.)?(\w)+(\.)(\w)+(\.)(\w|\/){2,10}$/';
SELECT * FROM `front` WHERE `domain` REGEXP '/^(http:\/\/)(www\.)?(\w)+(\.)(\w)+(\.)(\w|\/){2,10}$/g';
Which all return 0 records.
TL;DR
My working REGEX does not seem to be working when used in MySQL's REGEXP function.
There is no \w metacharacter support in MySQL. Use [A-Za-z0-9_] instead:
SELECT * FROM `front` WHERE `domain` REGEXP '^(http:\/\/)(www\.)?([A-Za-z0-9_])+(\.)([A-Za-z0-9_])+(.)([A-Za-z0-9_]|\/){2,10}$';
It's right there in the documentation:
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.
Related
How would I do the following in mysql?
SELECT * FROM table WHERE search REGEXP '.+season\d+\s?.+' limit 10;
I want to match something like:
"hello this is season1 how are you?"
But not:
"hello this is season1episode1 how are you?
You can use the following regular expression since \d and \s are not available on MySQL. You can use character classes instead.
You can replace \d with [[:digit:]] or [0-9] and \s with [[= =]] or [ ].
SELECT * FROM table WHERE search REGEXP '.+season[[:digit:]]+[[= =]].+' LIMIT 10
-- or...
SELECT * FROM table WHERE search REGEXP '.+season[0-9]+[ ].+' LIMIT 10
demo on dbfiddle.uk
Before MySQL 8.0,
REGEXP "season[0-9]+[[:>:]]"
meaning "season", at least one digit, then a word boundary. Note that it will stop with punctuation.
REGEXP "season[0-9]+[^a-zA-Z]"
Might work for you -- it says that it should be followed by a letter.
8.0 changes the word boundary to:
REGEXP "season[0-9]+\b"
(Caveat: the backslash may need to be doubled up.)
I'm trying to select all rows that contain only alphanumeric characters in MySQL using:
SELECT * FROM table WHERE column REGEXP '[A-Za-z0-9]';
However, it's returning all rows, regardless of the fact that they contain non-alphanumeric characters.
Try this code:
SELECT * FROM table WHERE column REGEXP '^[A-Za-z0-9]+$'
This makes sure that all characters match.
Your statement matches any string that contains a letter or digit anywhere, even if it contains other non-alphanumeric characters. Try this:
SELECT * FROM table WHERE column REGEXP '^[A-Za-z0-9]+$';
^ and $ require the entire string to match rather than just any portion of it, and + looks for 1 or more alphanumberic characters.
You could also use a named character class if you prefer:
SELECT * FROM table WHERE column REGEXP '^[[:alnum:]]+$';
Try this:
REGEXP '^[a-z0-9]+$'
As regexp is not case sensitive except for binary fields.
There is also this:
select m from table where not regexp_like(m, '^[0-9]\d+$')
which selects the rows that contains characters from the column you want (which is m in the example but you can change).
Most of the combinations don't work properly in Oracle platforms but this does. Sharing for future reference.
Try this
select count(*) from table where cast(col as double) is null;
Change the REGEXP to Like
SELECT * FROM table_name WHERE column_name like '%[^a-zA-Z0-9]%'
this one works fine
I've been to the regexp page on the MySQL website and am having trouble getting the query right. I have a list of links and I want to find invalid links that do not contain a period. Here's my code that doesn't work:
select * from `links` where (url REGEXP '[^\\.]')
It's returning all rows in the entire database. I just want it to show me the rows where 'url' doesn't contain a period. Thanks for your help!
SELECT c1 FROM t1 WHERE c1 NOT LIKE '%.%'
Your regexp matches anything that contains a character that isn't a period. So if it contains foo.bar, the regexp matches the f and succeeds. You can do:
WHERE url REGEXP '^[^.]*$'
The anchors and repetition operator make this check that every character is not a period. Or you can do:
WHERE LOCATE(url, '.') = 0
BTW, you don't need to escape . when it's inside [] in a regexp.
Using regexp seems like an overkill here. A simple like operator would do the trick:
SELECT * FROM `links` WHERE url NOT LIKE '%.%
EDIT:
Having said that, if you really want to negate regexp, just use not regexp:
SELECT * FROM `links` WHERE url NOT REGEXP '[\\.]';
I have a table, such as
create table table1(
name varchar(32),
);
And there's some data in it. When I select like this:
select * from table1 where name like 'Jack2%';
there will be Jack2.
But if I select like this:
select * from table1 where name like 'Jack[0-9]%';
there will be nothing;
And I also tried regexp to subsitute like, but it also didn't work!
What's wrong?
You've confused two different pattern-matching mechanisms. SQL LIKE uses % to match anything and _ to match any single character; it does not have anything like [0-9] to match a digit. That looks like a character class from a regular expression.
Standard SQL has no support for regular expressions at all, but MySQL does - you just have to use RLIKE (or REGEXP, but that doesn't read as nicely IMO) instead of LIKE. But that means that you have to replace the % with the regular-expression equivalent .*, too.
SELECT * FROM table1 WHERE name RLIKE 'Jack[0-9].*';
Fiddle
MySQL REGEX
select * from Table1 where `name` REGEXP 'Jack[0-9]'
You can use RLIKE instead
SELECT * FROM table1 WHERE name RLIKE 'Jack[0-9].*';
And please note the the '%' operator won't work with RLIKE, you have to use a regular expression pattern like '.*' instead.
SELECT * FROM t WHERE c REGEXP '.*\(..\).*';
This didn't work. It returned many rows whose c contain string that have more than two characters in ().
SELECT * FROM t WHERE c LIKE '%(__)%'
SQL Fiddle here
Your escapes are off.
http://dev.mysql.com/doc/refman/5.0/en/regexp.html#operator_regexp
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.
Use:
SELECT * FROM t WHERE c REGEXP '.*\\(..\\).*';
How are you running this query? If you're using it in (say) a PHP script, and writing it like this:
$sql = "SELECT ... REGEXP '.*\(..\).*';";
then the PHP interpreter will actually be stripping out those backslashes, producing the real query
... REGEXP '.*(..).*';
which would simply be any record that has at least two characters. For this to work properly, you'll have to double-escape:
$sql = "SELECT ... REGEXP '.*\\(..\\).*';";
PHP will strip off one of the backslashes from each set, leaving the second one to actually reach mysql.