Case Insensitivity of MySQL - mysql

Hello everyone I am using MySQL 5.0, but when I fire my queries through my web application that is in Java they are case insensitive.
First query:
select * from market where company='"abc"'
Second query:
select 8 from market where company='"ABC"'
Both queries give me same results. I just want rows with company "abc" only and not ABC.
How I can solve this problem? Thanks.

You need to set the proper collation.
http://dev.mysql.com/doc/refman/5.0/en/case-sensitivity.html

You can use a binary collation for the field, for instance utf8_bin
http://dev.mysql.com/doc/refman/5.0/en/case-sensitivity.html
If you want to do always case sensitive searches on that field, you can use an alter table to set utf8_bin, or another binary collation, for example:
ALTER TABLE `market` CHANGE `company` `company` VARCHAR( 255 )
CHARACTER SET utf8 COLLATE utf8_bin NULL DEFAULT NULL

Related

Laravel: How to create table with case sensitive column (binary)?

I would like to use base62 unique identifiers and my problem is that the columns are not case sensitive, so F1 is the same as f1 when I search for it. Now in MYSQL I would simply do
CREATE TABLE USERS
(
USER_NAME STRING(10) BINARY
)
So in Laravel it should look like
$table->string('base62_id', 10)->binary();
However, I don't think ->binary() exists in laravel for this purpose. So how would I do that?
I understand this question is old, but in case anyone stumbles upon it. At time of writing, Laravel is version 8 and this is valid:
$table->string("case_sensitive_id")->charset("utf8")->collation("utf8_bin")->nullable();
This will achieve case sensitivity without any sort of alter statements.
So this is the answer:
DB::statement("ALTER TABLE `mytable` ADD `base62_id` VARCHAR( 10 ) CHARACTER SET utf8 COLLATE utf8_bin UNIQUE AFTER `id` , ADD INDEX ( `base62_id` )");
The key is to use
CHARACTER SET utf8 COLLATE utf8_bin
to make it case sensitive.
Thank you # my source: http://blog.birdhouse.org/2010/10/24/base62-urls-django/comment-page-1/

MySql table columns have different CHARSET and COLLATION even when SELECT data is from the same source table and column?

In creating a simple (temporary) MySQL table, taking data from the same column of the same source table, the two resulting columns wind up with different CHARACTER SET and resulting default COLLATION settings:
mysql> CREATE TABLE tempDates
SELECT SUBDATE(MAX(EventDate), INTERVAL 90 DAY) AS StartDate,
MAX(EventDate) AS EndDate FROM james_bond_007
WHERE EventCategory = 'Successful_Kills';
Here is the output showing the resulting table structures:
mysql> SHOW CREATE TABLE tempDates;
CREATE TABLE `tempDates` (
`StartDate` varchar(29) CHARACTER SET utf8 DEFAULT NULL,
`EndDate` varchar(255) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1
I ran an alter table command, but NOTHING changed:
ALTER TABLE tempdates CHARACTER SET latin1 COLLATE latin1_swedish_ci;
From a curiosity standpoint, I want to know why this happens, and from a practical standpoint, how do I make this not happen?
The result I want is for all columns to have the server defaults: CHARACTER SET latin1 COLLATE latin1_swedish_ci
Even better would be a way to impose the server defaults on all columns so I don't have to type more than I want to in future queries of this type.
#Rick James
This solved my problem so I want to mark it answered.
If you've a moment, perhaps an explanation as to why? (gives me another excuse to upvote you and accept your answer)

Illegal mix of collations (utf8_unicode_ci,IMPLICIT) and (utf8_general_ci,IMPLICIT) for operation '='

Error message on MySql:
Illegal mix of collations (utf8_unicode_ci,IMPLICIT) and (utf8_general_ci,IMPLICIT) for operation '='
I have gone through several other posts and was not able to solve this problem.
The part affected is something similar to this:
CREATE TABLE users (
userID INT UNSIGNED NOT NULL AUTO_INCREMENT,
firstName VARCHAR(24) NOT NULL,
lastName VARCHAR(24) NOT NULL,
username VARCHAR(24) NOT NULL,
password VARCHAR(40) NOT NULL,
PRIMARY KEY (userid)
) ENGINE = INNODB CHARACTER SET utf8 COLLATE utf8_unicode_ci;
CREATE TABLE products (
productID INT UNSIGNED NOT NULL AUTO_INCREMENT,
title VARCHAR(104) NOT NULL,
picturePath VARCHAR(104) NULL,
pictureThumb VARCHAR(104) NULL,
creationDate DATE NOT NULL,
closeDate DATE NULL,
deleteDate DATE NULL,
varPath VARCHAR(104) NULL,
isPublic TINYINT(1) UNSIGNED NOT NULL DEFAULT '1',
PRIMARY KEY (productID)
) ENGINE = INNODB CHARACTER SET utf8 COLLATE utf8_unicode_ci;
CREATE TABLE productUsers (
productID INT UNSIGNED NOT NULL,
userID INT UNSIGNED NOT NULL,
permission VARCHAR(16) NOT NULL,
PRIMARY KEY (productID,userID),
FOREIGN KEY (productID) REFERENCES products (productID) ON DELETE RESTRICT ON UPDATE NO ACTION,
FOREIGN KEY (userID) REFERENCES users (userID) ON DELETE RESTRICT ON UPDATE NO ACTION
) ENGINE = INNODB CHARACTER SET utf8 COLLATE utf8_unicode_ci;
The stored procedure I'm using is this:
CREATE PROCEDURE updateProductUsers (IN rUsername VARCHAR(24),IN rProductID INT UNSIGNED,IN rPerm VARCHAR(16))
BEGIN
UPDATE productUsers
INNER JOIN users
ON productUsers.userID = users.userID
SET productUsers.permission = rPerm
WHERE users.username = rUsername
AND productUsers.productID = rProductID;
END
I was testing with php, but the same error is given with SQLyog.
I have also tested recreating the entire DB but to no good.
Any help will be much appreciated.
The default collation for stored procedure parameters is utf8_general_ci and you can't mix collations, so you have four options:
Option 1: add COLLATE to your input variable:
SET #rUsername = ‘aname’ COLLATE utf8_unicode_ci; -- COLLATE added
CALL updateProductUsers(#rUsername, #rProductID, #rPerm);
Option 2: add COLLATE to the WHERE clause:
CREATE PROCEDURE updateProductUsers(
IN rUsername VARCHAR(24),
IN rProductID INT UNSIGNED,
IN rPerm VARCHAR(16))
BEGIN
UPDATE productUsers
INNER JOIN users
ON productUsers.userID = users.userID
SET productUsers.permission = rPerm
WHERE users.username = rUsername COLLATE utf8_unicode_ci -- COLLATE added
AND productUsers.productID = rProductID;
END
Option 3: add it to the IN parameter definition (pre-MySQL 5.7):
CREATE PROCEDURE updateProductUsers(
IN rUsername VARCHAR(24) COLLATE utf8_unicode_ci, -- COLLATE added
IN rProductID INT UNSIGNED,
IN rPerm VARCHAR(16))
BEGIN
UPDATE productUsers
INNER JOIN users
ON productUsers.userID = users.userID
SET productUsers.permission = rPerm
WHERE users.username = rUsername
AND productUsers.productID = rProductID;
END
Option 4: alter the field itself:
ALTER TABLE users CHARACTER SET utf8 COLLATE utf8_general_ci;
Unless you need to sort data in Unicode order, I would suggest altering all your tables to use utf8_general_ci collation, as it requires no code changes, and will speed sorts up slightly.
UPDATE: utf8mb4/utf8mb4_unicode_ci is now the preferred character set/collation method. utf8_general_ci is advised against, as the performance improvement is negligible. See https://stackoverflow.com/a/766996/1432614
I spent half a day searching for answers to an identical "Illegal mix of collations" error with conflicts between utf8_unicode_ci and utf8_general_ci.
I found that some columns in my database were not specifically collated utf8_unicode_ci. It seems mysql implicitly collated these columns utf8_general_ci.
Specifically, running a 'SHOW CREATE TABLE table1' query outputted something like the following:
| table1 | CREATE TABLE `table1` (
`id` int(11) NOT NULL,
`col1` varchar(4) CHARACTER SET utf8 NOT NULL,
`col2` int(11) NOT NULL,
PRIMARY KEY (`col1`,`col2`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci |
Note the line 'col1' varchar(4) CHARACTER SET utf8 NOT NULL does not have a collation specified. I then ran the following query:
ALTER TABLE table1 CHANGE col1 col1 VARCHAR(4) CHARACTER SET utf8
COLLATE utf8_unicode_ci NOT NULL;
This solved my "Illegal mix of collations" error. Hope this might help someone else out there.
I had a similar problem, but it occurred to me inside procedure, when my query param was set using variable e.g. SET #value='foo'.
What was causing this was mismatched collation_connection and Database collation. Changed collation_connection to match collation_database and problem went away. I think this is more elegant approach than adding COLLATE after param/value.
To sum up: all collations must match. Use SHOW VARIABLES and make sure collation_connection and collation_database match (also check table collation using SHOW TABLE STATUS [table_name]).
A bit similar to #bpile answer, my case was a my.cnf entry setting collation-server = utf8_general_ci. After I realized that (and after trying everything above), I forcefully switched my database to utf8_general_ci instead of utf8_unicode_ci and that was it:
ALTER DATABASE `db` CHARACTER SET utf8 COLLATE utf8_general_ci;
Answer is adding to #Sebas' answer - setting the collation of my local environment. Do not try this on production.
ALTER DATABASE databasename CHARACTER SET utf8 COLLATE utf8_unicode_ci;
ALTER TABLE tablename CONVERT TO CHARACTER SET utf8 COLLATE utf8_unicode_ci;
Source of this solution
In my own case I have the following error
Illegal mix of collations (utf8_general_ci,IMPLICIT) and (utf8_unicode_ci,IMPLICIT) for operation '='
$this->db->select("users.username as matric_no, CONCAT(users.surname,
' ',
users.first_name, ' ', users.last_name) as fullname")
->join('users', 'users.username=classroom_students.matric_no', 'left')
->where('classroom_students.session_id', $session)
->where('classroom_students.level_id', $level)
->where('classroom_students.dept_id', $dept);
After weeks of google searching I noticed that the two fields I am comparing consists of different collation name. The first one i.e username is of utf8_general_ci while the second one is of utf8_unicode_ci so I went back to the structure of the second table and changed the second field (matric_no) to utf8_general_ci and it worked like a charm.
Despite finding an enormous number of question about the same problem (1, 2, 3, 4) I have never found an answer that took performance into consideration, even here.
Although multiple working solutions has been already given I would like to do a performance consideration.
EDIT: Thanks to Manatax for pointing out that option 1 does not suffer of performance issues.
Using Option 1 and 2, aka the COLLATE cast approach, can lead to potential bottleneck, cause any index defined on the column will not be used causing a full scan.
Even though I did not try out Option 3, my hunch is that it will suffer the same consequences of option 1 and 2.
Lastly, Option 4 is the best option for very large tables when it is viable. I mean there are no other usage that rely on the original collation.
Consider this simplified query:
SELECT
*
FROM
schema1.table1 AS T1
LEFT JOIN
schema2.table2 AS T2 ON T2.CUI = T1.CUI
WHERE
T1.cui IN ('C0271662' , 'C2919021')
;
In my original example, I had many more joins.
Of course, table1 and table2 have different collations.
Using the collate operator to cast, it will lead to indexes not being used.
See sql explanation in the picture below.
Visual Query Explanation when using the COLLATE cast
On the other hand, option 4 can take advantages of possible index and led to fast queries.
In the picture below, you can see the same query being run after applied Option 4, aka altering the schema/table/column collation.
Visual Query Explanation after the collation has been changed, and therefore without the collate cast
In conclusion, if performance are important and you can alter the collation of the table, go for Option 4.
If you have to act on a single column, you can use something like this:
ALTER TABLE schema1.table1 MODIFY `field` VARCHAR(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
This happens where a column is explicitly set to a different collation or the default collation is different in the table queried.
if you have many tables you want to change collation on run this query:
select concat('ALTER TABLE ', t.table_name , ' CONVERT TO CHARACTER
SET utf8 COLLATE utf8_unicode_ci;') from (SELECT table_name FROM
information_schema.tables where table_schema='SCHRMA') t;
this will output the queries needed to convert all the tables to use the correct collation per column
I was also facing a problem while upload excels file in MySql Database form Laravel. In excel file some addresses contain characters like PeterÕs that Error was
SQLSTATE[HY000]: General error: 1267 Illegal mix of collations (latin1_swedish_ci,IMPLICIT) and (utf8mb4_unicode_ci,COERCIBLE) for operation '=' (SQL: select count(*) as aggregate from `.....` where `e....` = kas#email.com and `first_name` = Gill and `surname` = Harries and `address` = 6 St.PeterÕs Close,,,Woodbridge,Suffolk,IP12 4EJ and `status` = 1 and `client`.`deleted_at` is null)
I try many solutions that is mentioned above but unfortunately, no one works for me. so I post the solution that works for me. so maybe it will not work in some situations. Exception can be different. so you have to find a solution based on that. please vote Up if some finds this is useful.
I try 2 types of solutions.
I putted my exceptional code into try{} Catch() block for handling. because it was giving an error while executing select() query. so that I use TRY{} for this. using that uploaded record stored in the database. But when charset issue comes on that place it is put ?. that sample image is given below.
you can detect the charset that gives an issue while operating and change the MySql configuration by this code
\Config::set('database.connections.mysql.charset', 'latin1');
\Config::set('database.connections.mysql.collation', 'latin1_bin');
\DB::purge('mysql');
Both solution works for me.

Case sensitive find in Rails

I'm using Mysql with collation utf8_general_ci and for most of my searches it is good. But for one model and one field I want to find a record with case sensitive. How to do it?
It is MySQL that is doing the case insensitive query, not Ruby on Rails.
See http://dev.mysql.com/doc/refman/5.0/en/case-sensitivity.html
You could make database columns, that require case sensitivity to be case sensitive
Modify fields to be BINARY or VARBINARY instead of CHAR and VARCHAR.
Modify fields to have binary collation (e.g. latin1_bin)
-
create table tbl_name (
...
data varchar COLLATE latin1_bin
)
Or you can modify your queries to use COLLATE operator:
SELECT * from tbl_name WHERE col_name COLLATE latin1_bin LIKE 'a%'
If you always want to search that column in a case sensitive manner, the best thing would be to define it with collation utf8_bin

MySQL error: "Column 'columnname' cannot be part of FULLTEXT index"

Recently I changed a bunch of columns to utf8_general_ci (the default UTF-8 collation) but when attempting to change a particular column, I received the MySQL error:
Column 'node_content' cannot be part of FULLTEXT index
In looking through docs, it appears that MySQL has a problem with FULLTEXT indexes on some multi-byte charsets such as UCS-2, but that it should work on UTF-8.
I'm on the latest stable MySQL 5.0.x release (5.0.77 I believe).
Oops, so I have found the answer to my problem:
All columns of a FULLTEXT index must have not only the same character set but also the same collation.
My FULLTEXT index had utf8_unicode_ci on one of its columns, and utf8_general_ci on its other columns.
Just to add to Thomas's good advice: And to sort things out in PHPMyAdmin you have to change the characterset for all columns AT THE SAME TIME.
Just wasted half a day trying again and again to change the columns one at a time and continually getting the error message about the FULLTEXT index.
For DBeaver/database tool users.
When you use interface to modify more than one column, the tool generate commands like this :
ALTER TABLE databaseName.tableName MODIFY COLUMN columnName1 text CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL;
ALTER TABLE databaseName.tableName MODIFY COLUMN columnName2 varchar(128) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL;
This is not working because you must modify the charsets at the same time.
So, you have to change it manually, in one command :
ALTER TABLE databaseName.tableName
MODIFY COLUMN columnName1 text CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL,
MODIFY COLUMN columnName2 text CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL;
utf8 or utf8mb4 ? See here.