11/10/2023 0 Comments Mysql list databases with colaltion![]() ![]() But the correct solution will depend on your actual data set and the needs of your application. For Swedish data, an alternative may be utf8mb4_sv_0900_ai_ci, which share many properties with latin1_swedish_ci. In this situation, you must consider which collation you really want. If this column is changed to utf8mb4 which has the default collation utf8mb4_0900_ai_ci in MySQL 8.0, unique constraint may be broken, since in this collation, ‘a’=’å’=’ä’ and ‘o’=ö’. The simplest example is if you have create a character column with default settings in MySQL 5.7, this column will have the character set latin1 which again has the default collation latin1_swedish_ci. Since collations are different, changing the character set of a table may break unique constraints (UNIQUE or PRIMARY KEY etc.). For large data volumes, this may take considerable time and the table will be locked during index generation. When collation of a column changes, even if the character set stays the same, indices will be regenerated. So if you have key varchar/char columns with lengths larger than 767 characters you will have to consider either to shorten the length, change to TEXT or change the InnoDB settings. This value is dependent upon InnoDB row format and innodb_page_size, so you will need to check the documentation to figure out what your limit is if you don’t run with default settings.Ī utf8mb4 character use 1-4 bytes, which means that the maximum length of a char/varchar column that is a key, will be 767 characters. InnoDB tables have a max key length of 3072 bytes. Then you need to have a look at some properties of these columns. So, to take advantage of the new collations for existing applications that have upgraded from 5.7, one need to do a migration project.įirst, you need to analyze your schemata and figure out which columns should be in utf8mb4. Now if you want to change the existing data. Col2 VARCHAR ( 100 ) COLLATE AS utf8mb4_sv_0900_ai_ciĬol1 get the collation utf8mb4_0900_ai_ci, and col2 get the character set utf8mb4. Changing the collation of a database will only affect new tables you create in that database, but it's easy to do: look for the 'Collation' dropdown from the database's 'Operations' tab: You can go further and similarly change the table-level collation, again from the Operations tab of each table. If ($QUERY = "ALTER TABLE `$db`.`$tb_name`\n") continue This has helped, all fields in the tables are also converted. I was just adding another loop for the fields within the tables to the solution via Php before mentioned. ![]() To change the collation of all fields in all tables of a database at once: ![]() Returns information about the altered tables or 'No records'Īfter the procedure is created call it simply: CALL changeCollation('utf8') ' was changed to the default collation of ', character_set, SET v_message = CONCAT('The table ', v_table_name , ' CONVERT TO CHARACTER SET ', character_set) SET = CONCAT('ALTER TABLE ',v_table_name, that this one is different by each iteration inside the loop that is based on the v_table_name parameter and it means This technic makes the trick, it prepares a statement If there is no more record, then we have to skip Start a loop to fetch each rows from the cursor This handler will set the value v_finished to 1 where the character set is not the oneĭECLARE alter_cursor CURSOR FOR SELECT DISTINCT TABLE_NAMEįROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_SCHEMA = DATABASE()ĪND COLLATION_NAME NOT LIKE CONCAT(character_set, '_%') This will create a cursor that selects each table, or 'latin1' or any other valid character setĬREATE PROCEDURE changeCollation(IN character_set VARCHAR(255))ĭECLARE v_table_name varchar(255) DEFAULT "" ĭECLARE v_message varchar(4000) DEFAULT "No records" character_set parameter could be 'utf8' Here is a solution how to do it with a stored procedure: DELIMITER $$ĭROP PROCEDURE IF EXISTS changeCollation$$ I read it here, that you need to convert each table manually, it is not true. ![]() WHERE INFORMATION_SCHEMA =ĪND INFORMATION_NAME =ĪND DATA_TYPE IN ( 'char', 'varchar' ) /* include other types if necessary */ ), ' COLLATE utf8mb4_unicode_ci ') AS 'USE `DATABASE_NAME` 'ĪND (SELECT INFORMATION_TYPE OR DATA_TYPE LIKE 'longtext', '', CONCAT('(', CHARACTER_MAXIMUM_LENGTH, '` CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci ')ĮACH COLUMN SELECT CONCAT('ALTER TABLE `', TABLE_NAME, '` MODIFY COLUMN `', COLUMN_NAME,'` ',ĭATA_TYPE, IF(CHARACTER_MAXIMUM_LENGTH IS NULL To use, just export results to delimited text (probably new line '\n')ĮACH TABLE SELECT CONCAT('ALTER TABLE `', TABLE_NAME, I have used this to some of my projects before and was able to solved most of my COLLATION problems. Generates query to update each table and column of each table. ![]()
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