We have some tables that were set with the Latin character set instead of UTF-8 and it allowed bad characters to be entered into the tables, the usual culprit is people copy / pasting from Word or Outlook which copys those nasty hidden characters...
Is there any query we can use to identify these characters to clean them?
Thanks,
I assume that your connection chacater set was set to UTF8 when you filled the data in.
MySQL replaces unconvertable characters with ? (question marks):
SELECT CONVERT('тест' USING latin1);
----
????
The problem is distinguishing legitimate question marks from illegitimate ones.
Usually, the question marks in the beginning of a word are a bad sign, so this:
SELECT *
FROM mytable
WHERE myfield RLIKE '\\?[[:alnum:]]'
should give a good start.
You're probably noticing something like this 'bug'. The 'bad characters' are most likely UTF-8 control characters (eg \x80). You might be able to identify them using a query like
SELECT bar FROM foo WHERE bar LIKE LOCATE(UNHEX(80), bar)!=0
From that linked bug, they recommend using type BLOB to store text from windows files:
Use BLOB (with additional encoding field) instead of TEXT if you need to store windows files (even text files). Better than 3-byte UTF-8 and multi-tier encoding overhead.
Take a look at this Q/A (it's all about your client encoding aka SET NAMES )
Related
I have a text file that contains non english word and i need to put it into mysql how can i ?
203851 ኣብ
70351 ናይ
56687 ካብ
46018 እቲ
41928 ምስ
40221 ከም
38702 ድማ
29739 ናብ
28806 እዩ
23066 ከኣ
21459 ግን
21013 እዚ
20638 ሓደ
If by that you mean how can you insert a non-unicode string the answer is: the same way as you would put any other string. Just be careful when you create the column to select an encoding that supports it (for example utf8-mb4 - that means utf8 on 4 bytes, because the default mysql utf8 only uses 3 and... long story here actually :) - should do the trick for mostly anyhting you want to put there).
Then... INSERT INTO tableName (columnName) VALUES ('yourString');
Important note here: You should convert that string to the encoding you use before (again... utf8 would be your best choice). If you don't do that and respect the next paragraph (check below) you are still fine, but if you don't you will end up with messed up stuff.
Just be careful on data processing unfortunately mysql has so many points of failure regarding encoding. It has 1 encoding for db, 1 for table, 1 for column, 1 for data saving, even 1 for the connection so... just try to use the same for all to avoid surprises.
You have a text file with 2 columns of data? Are they separated by tabs or what?
Use LOAD DATA INFILE with suitable parameters.
I just found myself lost in the interesting situation that I need to query MySQL for fields containing a so called Left-to-right mark.
As the nature of this character is to be non-printing, thus invisible, I'm unable to simply copy/paste it into a query.
As mentioned in the linked Wikipedia article, the Left-to-right mark is Unicode character U+200F, which is a fact that I'm sure is the key to success in my current adventure.
My question is: How do I use raw Unicode in a MySQL query? Something along the lines of:
SELECT * FROM users WHERE username LIKE '%\U+200F%'
or
SELECT * FROM users WHERE username REGEXP '\U+200F'
or whatever the correct syntax for Unicode in MySQL is and depending on whether this is supported with LIKE and/or REGEXP.
To get a unicode char, something like this should work:
SELECT CHAR(<number> USING utf8);
Also, don't use REGEXP, because the regexp lib used by MySQL is very old, and doesn't support multi-byte charsets.
Somewhere along the way, between all the imports and exports I have done, a lot of the text on a blog I run is full of weird accented A characters.
When I export the data using mysqldump and load it into a text editor with the intention of using search-and-replace to clear out the bad characters, searching just matches every "a" character.
Does anyone know any way I can successfully hunt down these characters and get rid of them, either directly in MySQL or by using mysqldump and then reimporting the content?
This is an encoding problem; the  is a non-breaking space (HTML entity ) in Unicode being displayed in Latin1.
You might try something like this... first we check to make sure the matching is working:
SELECT * FROM some_table WHERE some_field LIKE BINARY '%Â%'
This should return any rows in some_table where some_field has a bad character. Assuming that works properly and you find the rows you're looking for, try this:
UPDATE some_table SET some_field = REPLACE( some_field, BINARY 'Â', '' )
And that should remove those characters (based on the page you linked, you don't really want an nbsp there as you would end up with three spaces in a row between sentences etc, you should only have one).
If it doesn't work then you'll need to look at the encoding and collation being used.
EDIT: Just added BINARY to the strings; this should hopefully make it work regardless of encoding.
The accepted answer did not work for me.
From here http://nicj.net/mysql-converting-an-incorrect-latin1-column-to-utf8/ I have found that the binary code for  character is c2a0 (by converting the column to VARBINARY and looking what it turns to).
Then here http://www.oneminuteinfo.com/2013/11/mysql-replace-non-ascii-characters.html found the actual solution to remove (replace) it:
update entry set english_translation = unhex(replace(hex(english_translation),'C2A0','20')) where entry_id = 4008;
The query above replaces it to a space, then a normal trim can be applied or simply replace to '' instead.
I have had this problem and it is annoying, but solvable. As well as  you may find you have a whole load of characters showing up in your data like these:
“
This is connected to encoding changes in the database, but so long as you do not have any of these characters in your database that you want to keep (e.g. if you are actually using a Euro symbol) then you can strip them out with a few MySQL commands as previously suggested.
In my case I had this problem with a Wordpress database that I had inherited, and I found a useful set of pre-formed queries that work for Wordpress here http://digwp.com/2011/07/clean-up-weird-characters-in-database/
It's also worth noting that one of the causes of the problem in the first place is opening a database in a text editor which might change the encoding in some way. So if you can possibly manipulate the database using MySQL only and not a text editor this will reduce the risk of causing further trouble.
I have a couple escaped characters in user-entered fields that I can't figure out.
I know they are the "smart" single and double quotes, but I don't know how to search for them in mysql.
The characters in ruby, when output from Ruby look like \222, \223, \224 etc
irb> "\222".length => 1
So - do you know how to search for these in mysql? When I look in mysql, they look like '?'.
I'd like to find all records that have this character in the text field. I tried
mysql> select id from table where field LIKE '%\222%'
but that did not work.
Some more information - after doing a mysqldump, this is how one of the characters is represented - '\\xE2\\x80\\x99'. It's the smart single quote.
Ultimately, I'm building an RTF file and the characters are coming out completely wrong, so I'm trying to replace them with 'dumb' quotes for now. I was able to do a gsub(/\222\, "'").
Thanks.
I don't quite understand your problem but here is some info for you:
First, there are no escaped characters in the database. Because every character being stored as is, with no escaping.
they don't "look ilke ?". I's just wrong terminal settings. SET NAMES query always should be executed first, to match client encoding.
you have to determine character set and use it on every stage - in the database, in the mysql client, in ruby.
you should distinguish ruby strings representation from character itself.
To enter character in the mysql query, you can use char function. But in terminal only. In ruby just use the character itself.
smart quotes looks like 2-byte encoded in the unicode. You have to determine your encoding first.
I have a table with a field which contains strings in my MySQL database.
The MySQL version is 5.0.51a. The default character set for the table is 'utf8'.
Many of the strings have unicode characters such as \xae and \u21222 (registered symbol and trademark symbol respectively).
For example, suppose I have a row with a field this value:
"Bing® Blang™ Blaow"
The default character set of my mysql command line client is "latin1".
If I issue a SELECT statement in the mysql client program from the command line without specifying a character set, the output of the title shows up like so:
"Bing® Blang Blaow"
The (R) symbol is correct but the (TM) symbol is missing. If I cut and paste this string from the console into TextMate, the (TM) symbol appears, but is half-way behind the g in the word "Blang".
I am assuming that the half-way-behind-the-g thing is a just a display error in TextMate (though if anyone can provide further detail that'd be great, but that's not really the important part).
The main thing I am inferring from the its-there-after-you-cut-and-paste behavior is that the data is in the database but there's something wrong with some sort of character set setting somewhere.
If I override the default encoding of the mysql client on the command line like so:
mysql --default-character-set=utf8
Then do the same select, the string comes out as:
"Bing® Blang™ Blaow"
which is to say that both the (R) and (TM) symbols appear and are in the right place but both are preceded by the unicode character \xae which is an A with a circumflex on top.
(Incidentally this is also how the data is displayed when I pull it out using python and display it on a web page, which is what my real problem is).
Anyway, what is going on here? Everything we have done recently has used UTF8 everywhere possible, but it's possible that some of these rows were inserted prior to that change which means they would've been using the latin1 default... however neither encoding seems to produce the right result?
If the rows were inserted when the default encoding on the table was latin1 before it was switched to utf8, then the encoding was switched (via alter table..) then would the encoding have actually been updated? Should one of the encodings work now? Will unicode ever stop kicking my ass?
There are quite a number of issues here:
About the characters
You indicate that the text has characters U+AE and U+2122 (® and ™ respectively). However, the results imply that the text has U+99 as the character after "Blang": When you set MySQL to output UTF8, then you see this "™" -- which is the UTF8 sequence for U+99 displayed on a terminal that is interpreting this byte stream as Windows-1252.
U+99 probably isn't what you wanted: In Unicode, that is an extended control character with no graphic representation. It just so happens that in Windows-1252, that 0x99 is the encoding of the trademark symbol (U+2122).
(Please note that both MySQL and most web browsers have a common, "broken" behavior of using Windows-1252 when you choose Latin1. Sigh.)
What's probably wrong
Your terminal isn't operating in the right character set. It is clearly operating in Windows-1252.
Programs should be connecting to the database in UTF-8. You can do that in the command line, as you've found, or by executing the statement SET NAMES utf8_general_ci; in your database handle before doing anything else. Some other database APIs may have other ways of doing this, but there is no generic way for all SQL engines. SET NAMES ... is specific to MySQL, but sets all the required character set variables (there are three!) at once.
The process that is inserting data into the database is taking user input and not correctly converting it from Windows-1252 into UTF-8 before inserting. This is how you got a U+99 into your database. Since I don't know how you are getting that data, I'm not sure what to fix, but here are several possibilities:
If the data comes from a web page form, be sure the page with the form is served in UTF-8, is properly marked as such (via the MIME Type, and the <meta> tag.) Be sure also, that the <form> tag is not specifying a different character set.
When converting the data, be sure that you use iconv or similar libraries to convert from the input character set to UTF-8. Even if you think the input is Latin1, do not try to do this by hand (for example, by zero expanding every byte to 16-bits then claiming this is UTF-16 - that won't work for Windwos-1252!). Make absolutely certain that you know the character set of the source data. In particular, be sure to know if it is Latin1 or Windows-1252.
Instead of converting the user input, you could connect to the database in character set of the user input, and then just insert the raw byte data you get from the user. However, you must be sure to only do insertions this way: reading back data from the data with the user's character set in effect will lose information if other rows have data that can't be represented in that character set. It is possible to set up a MySQL connection so that you issue statements in one character set and read results back in another... But it isn't for the faint of heart, and future programmers will likely go nuts trying to understand why the code does this.
If, when you pull the data out with Python and display it in a web page, you see the string "™", then that is indication that your are pulling the data out of the database correctly as UTF-8, but then putting it into a web page that is not correctly identified as UTF-8. Probably it is just defaulting to Latin1, which as noted above will really be Windows-1252.
Nonetheless, even if you fix the display, note that the data base has bad data in it, since U+99 isn't really the trademark symbol in a UTF-8 column. You'll need to clean up your data, by reading all the data, and replacing any characters in the range of U+80 through U+9F with what they were likely to have been, assuming the data was really Windows-1252. If you're not certain what character set the data was in originally -- then this data is, alas, just junk.
About changing character sets of tables
Converting the character set and collation of the table after inserting data will convert the columns, but, of course, any data already inserted will have already lost whatever characters the original character set couldn't represent.
Be careful to note the difference between ALTER TABLE foo CONVERT TO CHARACTER SET ... and ALTER TABLE foo CHARACTER SET ... The later only changes the default character set for the table, and will not change any columns, even if they were set to the default at creation. (MySQL only uses the defaults at column creation time, it doesn't remember that a given column is "defaulted" not does it keep it in sync with the table's default.)
I think it has to do with the settings of the mysql connection in your Python code.
try setting conn.character_set_name or something like that, depends on the mysql connection lib you are using.
in case of MySQLdb it should be smthng like this:
def character_set_name(*args, **kwargs): return 'utf-8'
conn.character_set_name = new.instancemethod(character_set_name, conn, conn.__class__)
Could it be that some of the columns have an explicitly different character set than the table default?
something like this...?
ALTER TABLE tbl_name CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci