I made a small form for a website which stored the formdata with Aes_encrypt. The database that was used accidentally set the column type to varchar, and the collation to utf-8. Now when I run aes_decrypt, I get null as a result. Is there any way to still decrypt the data? Or is it now completely useless?
Thanks!
Related
I need to implement a sorted SELECT, on a specific encoding of a field, without CONVERT.
That is, normally I'd do it by
SELECT * FROM table ORDER BY CONVERT(field USING gbk) COLLATE gbk_chinese_ci
However for some reason CONVERT was not allowed. As a result, I tried to approach this by
ALTER TABLE table MODIFY field VARCHAR(xx) CHARACTER SET gbk COLLATE gbk_chinese_ci;
SELECT * FROM table ORDER BY field
It works. That's good. However I'm worried about encoding problems.
Connection to the MySQL server includes the parameters characterEncoding=utf8 and useUnicode=true. I couldn't yet find the explanation of these params in MySQL's official document, but I suppose these ensure that the communications between the client and the server should be in utf-8.
That brings the question. Does MySQL server implicitly convert data in utf-8 to gbk when it receives the data? Do the GET params only define the charset of communication rather than that of the final stored data?
Edit
Comments say that the server does convert them! Thanks guys!
My further confusion is that, only one of the fields is set to use gbk, while everything else has been left to use utf8. That means the server's charset should still be utf8 globally but gbk locally for that field only.
Suppose now I fire this line of script to the server
INSERT INTO table (field_gbk, field_utf8) VALUES ("a", "b");
Does the server:
Receive the whole statement in utf8;
Convert only "a" to gbk and stores it; and
Stores "b" as-is to the database?
Many thanks guys!
Yes.
You specify the encoding of in the client when you connect.
You specify the encoding ("Character set") of the column you are Inserting into.
MySQL converts from one encoding to the other as it INSERTs the rows. Similarly, it converts the other way when SELECTing.
The CONVERT function should not (normally) be used for anything.
You are using Java? characterEncoding=utf8 and useUnicode=true is what it uses for declaring the client side.
"gbk" for a single column? Find. That column will handled differently than other columns.
[Edit: my mistake, read the wrong column for the type, the one I'm inserting into is LONGTEXT, not varchar(190)]
I am working with an application that stores the majority of its information in a MySQL database (MySQL server 5.7). One particular value I'm looking at has a 255 character limit enforced by the GUI but, when I looked at that column in the table where it's stored, it's set to varchar(190). I confirmed that I can enter 255-character values in the GUI and that they are not truncated, as I expected.
How can a varchar(190) column store >190 characters? Are there any consequences to doing it this way?
I read 11.4.1 The CHAR and VARCHAR Types and it states that anything over the limit should be truncated.
The answer is that I can't. Misread the column types because that column is varchar(255) when the application builds the schema in PostgreSQL. It's longtext* in MySQL, which explains why I was able to get past the 190 characters. I tried inserting my 230 char test string into the varchar(190) column and it throws an error, as expected.
Need more coffee.
*not sure why longtext, when the application GUI limits input to 255 characters, but I'll need to ask the people who built it.
I imported a MySQL table dump from my server to my local system. I am using phpMyAdmin to view my local MySQL databases. The column that held emails shows as BLOB - instead of actual email.
When I press on "edit" it shows correct emails, but not on listing.
I am totally confused as why this happens. Can anyone suggest solution?
BLOB data type is meant to store arbitrary binary data (Binary Large OBject = BLOB), for example an image or another document. It does not make sense to show the value as-is. It would look the same as viewing an image in a text editor.
You have several options, depending on the version of phpMyAdmin you are using - which I unfortunately do not know.
Make phpMyAdmin show BLOB values by default.
Show BLOB values for a complete result set.
These two possibilities are covered by an already asked question.
But basically, this is just fighting symptoms instead of curing the disease. The question is: Why did you chose the email field to be a BLOB? Basically, a VARCHAR is enough. I do not know the MySQL version you are running, but since MySQL 5.0.3, a VARCHAR can be as large as 65k byte.
ALTER TABLE
`table`
CHANGE
`email` `email` VARCHAR(255) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL;
The query above changes the field email to a VARCHAR(255). Pay attention to the length you like to use, and to the character set and collation. But UTF-8 should be very fine in this case.
It shows the text of "Blob" as a placeholder as the blob datatype (which is the datatype that your emails are stored in) is vastly variable in size. For large Blob sizes, if the data were displayed, it could take up 100s + screens to display.
I need to convert a MySQL column to use BLOB instead of VARCHAR that's used to store encrypted data.
I can find all sorts of posts of how to convert from BLOB to VARCHAR, but cannot find anything for going from VARCHAR to BLOB.
Can someone tell me how to do this?
I figured it out by using:
alter table users change email email blob
I have a table with a BLOB field that I sometimes want to set to NULL. If I edit a row in phpMyAdmin, I can set non-blob fields to NULL, but all I can do with a BLOB field is upload a file. If the field already has a value, the only way I have found to NULL it is to type in an SQL query. This makes each row update a two-step process, which makes it more error-prone (not to mention irritating).
I haven't found anything about this in the manual. If it makes a difference, I'm using phpMyAdmin version 3.3.8.1.
I also have been perplexed by the inability to set BLOB columns to NULL in phpMyAdmin. Luckily this seems to have been recently fixed: phpMyAdmin 3.4.1 happily lets you set BLOB columns to NULL.