The answer is
I am contributing here, as the OP asked:
How to change collation of database, table, column?
The selected answer just states it on table level.
Changing it database wide:
ALTER DATABASE <database_name> CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
Changing it per table:
ALTER TABLE <table_name> CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
Good practice is to change it at table level as it'll change it for columns as well. Changing for specific column is for any specific case.
Changing collation for a specific column:
ALTER TABLE <table_name> MODIFY <column_name> VARCHAR(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
if you want to update the default charset on a schema:
ALTER SCHEMA MYSCHEMA DEFAULT CHARACTER SET utf8 DEFAULT COLLATE utf8_unicode_ci;
You can simple add this code to script file
//Database Connection
$host = 'localhost';
$db_name = 'your_database_name';
$db_user = 'your_database_user_name';
$db_pass = 'your_database_user_password';
$con = mysql_connect($host,$db_user,$db_pass);
if(!$con) { echo "Cannot connect to the database ";die();}
mysql_select_db($db_name);
$result=mysql_query('show tables');
while($tables = mysql_fetch_array($result)) {
foreach ($tables as $key => $value) {
mysql_query("ALTER TABLE $value CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci");
}
}
echo "The collation of your database has been successfully changed!";
I used the following shell script. It takes database name as a parameter and converts all tables to another charset and collation (given by another parameters or default value defined in the script).
#!/bin/bash
# mycollate.sh <database> [<charset> <collation>]
# changes MySQL/MariaDB charset and collation for one database - all tables and
# all columns in all tables
DB="$1"
CHARSET="$2"
COLL="$3"
[ -n "$DB" ] || exit 1
[ -n "$CHARSET" ] || CHARSET="utf8mb4"
[ -n "$COLL" ] || COLL="utf8mb4_general_ci"
echo $DB
echo "ALTER DATABASE $DB CHARACTER SET $CHARSET COLLATE $COLL;" | mysql
echo "USE $DB; SHOW TABLES;" | mysql -s | (
while read TABLE; do
echo $DB.$TABLE
echo "ALTER TABLE $TABLE CONVERT TO CHARACTER SET $CHARSET COLLATE $COLL;" | mysql $DB
done
)
You can change the CHARSET and COLLATION of all your tables through PHP script as follows. I like the answer of hkasera but the problem with it is that the query runs twice on each table. This code is almost the same except using MySqli instead of mysql and prevention of double querying. If I could vote up, I would have voted hkasera's answer up.
<?php
$conn1=new MySQLi("localhost","user","password","database");
if($conn1->connect_errno){
echo mysqli_connect_error();
exit;
}
$res=$conn1->query("show tables") or die($conn1->error);
while($tables=$res->fetch_array()){
$conn1->query("ALTER TABLE $tables[0] CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci") or die($conn1->error);
}
echo "The collation of your database has been successfully changed!";
$res->free();
$conn1->close();
?>
You can run a php script.
<?php
$con = mysql_connect('localhost','user','password');
if(!$con) { echo "Cannot connect to the database ";die();}
mysql_select_db('dbname');
$result=mysql_query('show tables');
while($tables = mysql_fetch_array($result)) {
foreach ($tables as $key => $value) {
mysql_query("ALTER TABLE $value CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci");
}}
echo "The collation of your database has been successfully changed!";
?>
I was surprised to learn, and so I had to come back here and report, that the excellent and well maintained Interconnect/it SAFE SEARCH AND REPLACE ON DATABASE script has some options for converting tables to utf8 / unicode, and even to convert to innodb. It's a script commonly used to migrate a database driven website (Wordpress, Drupal, Joomla, etc) from one domain to another.
To change collation for tables individually you can use,
ALTER TABLE mytable CONVERT TO CHARACTER SET utf8
To set default collation for the whole database,
ALTER DATABASE `databasename` DEFAULT CHARACTER SET utf8 COLLATE utf8_bin
or else,
Goto PhpMyAdmin->Operations->Collation.
There you an find the select box which contains all the exsiting collations. So that here you can change your collation. So here after database table will follows this collation while you are creating new column . No need of select collation while creating new columns.
If you run phpMyAdmin >> select database >> select table >> go to "Operations" tab >> in "Table options" section >> you can pick Collation from the drop down list >> and once you press {Go} at the top of the screen you will see a message:
Your SQL query has been executed successfully
and a script
ALTER TABLE `tableName` CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci
But it will NOT change the collations of existing columns. To do so you can use this script (this one also came from phpMyAdmin)
ALTER TABLE `tableName` CHANGE `Name` `Name` VARCHAR( 255 ) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL
I read it here, that you need to convert each table manually, it is not true. Here is a solution how to do it with a stored procedure:
DELIMITER $$
DROP PROCEDURE IF EXISTS changeCollation$$
-- character_set parameter could be 'utf8'
-- or 'latin1' or any other valid character set
CREATE PROCEDURE changeCollation(IN character_set VARCHAR(255))
BEGIN
DECLARE v_finished INTEGER DEFAULT 0;
DECLARE v_table_name varchar(255) DEFAULT "";
DECLARE v_message varchar(4000) DEFAULT "No records";
-- This will create a cursor that selects each table,
-- where the character set is not the one
-- that is defined in the parameter
DECLARE alter_cursor CURSOR FOR SELECT DISTINCT TABLE_NAME
FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_SCHEMA = DATABASE()
AND COLLATION_NAME NOT LIKE CONCAT(character_set, '_%');
-- This handler will set the value v_finished to 1
-- if there are no more rows
DECLARE CONTINUE HANDLER
FOR NOT FOUND SET v_finished = 1;
OPEN alter_cursor;
-- Start a loop to fetch each rows from the cursor
get_table: LOOP
-- Fetch the table names one by one
FETCH alter_cursor INTO v_table_name;
-- If there is no more record, then we have to skip
-- the commands inside the loop
IF v_finished = 1 THEN
LEAVE get_table;
END IF;
IF v_table_name != '' THEN
IF v_message = 'No records' THEN
SET v_message = '';
END IF;
-- This technic makes the trick, it prepares a statement
-- that is based on the v_table_name parameter and it means
-- that this one is different by each iteration inside the loop
SET @s = CONCAT('ALTER TABLE ',v_table_name,
' CONVERT TO CHARACTER SET ', character_set);
PREPARE stmt FROM @s;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
SET v_message = CONCAT('The table ', v_table_name ,
' was changed to the default collation of ', character_set,
'.\n', v_message);
SET v_table_name = '';
END IF;
-- Close the loop and the cursor
END LOOP get_table;
CLOSE alter_cursor;
-- Returns information about the altered tables or 'No records'
SELECT v_message;
END $$
DELIMITER ;
After the procedure is created call it simply:
CALL changeCollation('utf8');
For more details read this blog.
Better variant to generate SQL script by SQL request. It will not ruin defaults/nulls.
SELECT concat
(
'ALTER TABLE ',
t1.TABLE_SCHEMA,
'.',
t1.table_name,
' MODIFY ',
t1.column_name,
' ',
t1.column_type,
' CHARACTER SET utf8 COLLATE utf8_general_ci',
if(t1.is_nullable='YES', ' NULL', ' NOT NULL'),
if(t1.column_default is not null, concat(' DEFAULT \'', t1.column_default, '\''), ''),
';'
)
from
information_schema.columns t1
where
t1.TABLE_SCHEMA like 'your_table_here' AND
t1.COLLATION_NAME IS NOT NULL AND
t1.COLLATION_NAME NOT IN ('utf8_general_ci');
Just run this SQL to convert all database tables at once. Change your COLLATION and databaseName to what you need.
SELECT CONCAT("ALTER TABLE ", TABLE_SCHEMA, '.', TABLE_NAME," COLLATE utf8_general_ci;") AS ExecuteTheString
FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_SCHEMA="databaseName"
AND TABLE_TYPE="BASE TABLE";
Quick way - export to SQL file, use search and replace to change the text you need to change. Create new database, import the data and then rename the old database and the new one to the old name.
My solution is a combination of @Dzintars and @Quassnoi Answer.
SELECT CONCAT("ALTER TABLE ", TABLE_SCHEMA, '.', TABLE_NAME," CONVERT TO CHARACTER SET utf8mb4 ;") AS ExecuteTheString
FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_SCHEMA="<your-database>"
AND TABLE_TYPE="BASE TABLE";
By using CONVERT TO, this generates a scripts, which converts all the Tables of <your-database> to your requested encoding. This also changes the encoding of every column!
you can set default collation at several levels:
http://dev.mysql.com/doc/refman/5.0/en/charset-syntax.html
1) client 2) server default 3) database default 4) table default 5) column
I've just written a bash script to find all tables in a given database and covert them (and its columns).
Script is available here: https://github.com/Juddling/mysql-charset
To change the collation of all fields in all tables of a database at once:
I was just adding another loop for the fields within the tables to the solution via Php before mentioned. This has helped, all fields in the tables are also converted.
<?php
$con = mysql_connect('localhost','user','pw');
if(!$con) { echo "Cannot connect to the database ";die();}
mysql_select_db('database_name');
$result=mysql_query('show tables');
while($tables = mysql_fetch_array($result)) {
foreach ($tables as $key => $table) { // for each table
$sql = "ALTER TABLE $table CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci";
echo "\n".$sql;
mysql_query($sql);
$sql = "show fields in ".$table." where type like 'varchar%' or type like 'char%' or type='text' or type='mediumtext';";
$rs2=mysql_query($sql);
while( $rw2 = mysql_fetch_array($rs2) ){ // for each field in table
$sql = "ALTER TABLE `".$table."` CHANGE `".$rw2['Field']."` `".$rw2['Field']."` ".$rw2['Type']." CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL;";
echo "\n".$sql;
mysql_query($sql);
}
}
}
echo "The collation of your database has been successfully changed!";
?>}
Note, after changing the charset for database/table/column, you might need to actually convert the existing data (if you see, for example, something like "مطلوب توريد جÙ") with something like this:
update country set name = convert(cast(convert(name using latin1) as binary) using utf8), cn_flag = convert(cast(convert(cn_flag using latin1) as binary) using utf8), and so on..
While for converting database, tables and fields, I would suggest this answer from this thread which would generate a big set of queries that you will just copy at paste, here I couldn't find an automatic solution yet. Also be warned, if you will convert the same field twice you will get unrecoverable question marks: "???". You will also get this question marks if you will convert data before converting fields/tables.
The following query will generate ALTER queries that change the collation for all appropriate columns in all tables to a certain type (utf8_general_ci in my example below).
SELECT concat
(
'ALTER TABLE ',
t1.TABLE_SCHEMA,
'.',
t1.table_name,
' MODIFY ',
t1.column_name,
' ',
t1.data_type,
'(' ,
CHARACTER_MAXIMUM_LENGTH,
')',
' CHARACTER SET utf8 COLLATE utf8_general_ci;'
)
from
information_schema.columns t1
where
t1.TABLE_SCHEMA like 'you_db_name_goes_here' AND
t1.COLLATION_NAME IS NOT NULL AND
t1.COLLATION_NAME NOT IN ('utf8_general_ci');
Generates query to update each table and column of each table.
I have used this to some of my projects before and was able to solved most of my COLLATION problems. (especially on JOINS XD) Hope some of you find it useful.
To use, just export results to delimited text (probably new line '\n')
-- EACH TABLE
SELECT CONCAT('ALTER TABLE ', TABLE_NAME,' CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;') AS 'USE DATABASE_NAME;'
FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_SCHEMA = 'DATABASE_NAME'
AND TABLE_TYPE LIKE 'BASE TABLE'
-- EACH COLUMN
SELECT CONCAT('ALTER TABLE ', TABLE_NAME,' MODIFY COLUMN ', COLUMN_NAME,' ', DATA_TYPE, IF(CHARACTER_MAXIMUM_LENGTH IS NULL OR DATA_TYPE LIKE 'longtext', '', CONCAT('(',CHARACTER_MAXIMUM_LENGTH,')')),' COLLATE utf8mb4_unicode_ci;') AS 'USE DATABASE_NAME;'
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_SCHEMA = 'DATABASE_NAME' AND (SELECT INFORMATION_SCHEMA.TABLES.TABLE_TYPE FROM INFORMATION_SCHEMA.TABLES WHERE INFORMATION_SCHEMA.TABLES.TABLE_SCHEMA = INFORMATION_SCHEMA.COLUMNS.TABLE_SCHEMA AND INFORMATION_SCHEMA.TABLES.TABLE_NAME = INFORMATION_SCHEMA.COLUMNS.TABLE_NAME LIMIT 1) LIKE 'BASE TABLE' AND DATA_TYPE IN ('char','varchar') /* include other types if necessary */
Source: Stackoverflow.com