6/21/2023 0 Comments Mysql collate![]() ![]() Information_schema. ![]() Here’s how to check the database settings: SELECT SCHEMA_NAME 'database',Īnd to modify it: ALTER DATABASE neocamino CHARACTER SET = utf8mb4 COLLATE = utf8mb4_unicode_ci Ĭheck the settings: SELECT table_name, CCSA.character_set_name, llation_name For Rails developper, you can set it in your config/database.yml file: # config/database.yml For latin1: latin1_swedish_ci (case-insensitive) or latin1_binįor the examples below I’ll use a database called “neocamino”.For utf8: utf8_general_ci (case-insensitive) or utf8_bin.For utf8mb4: utf8mb4_unicode_ci (case-insensitive) or utf8mb4_bin.Your text content won’t have such special characters: latin1.You care about accents but not smileys: utf8.You care about accents and smileys: utf8mb4.For a case-sensitive collation, go for latin1_general_cs or latin1_bin. The default collation for latin1 encoding is latin1_swedish_ci (notice the “_ci” at the end). ![]() You’ll have to work around that in your queries. There doesn’t seem to be a collation that ignores case but not accents ( utf8_general_cs, for “case-sensitive”, is experimental and might not work for you). If you care about accents, go for utf8_bin (or utf8mb4_bin). With such a collation, lower/upper case and accents will be ignored in your searches and constraints on text columns. ![]() Notice the “_ci” part at the end? It means “case insensitive” and implicitly also “accents insensitive”. With utf8 you usually go with utf8_general_ci (or utf8mb4_unicode_ci with utf8mb4). If a query for “deja vu” should match records like “déjà vu”, you’ll want an accent-insensitive collation. If a query for “hello” should match records like “HeLLo”, you’ll want a case-insensitive collation. How about the collation?Īgain, the collation is used when comparing data, for example in a WHERE clause (equal or LIKE), or with unicity constraints on text columns. More info in this excellent article on the matter. So if a column was a varchar(256) in utf8, it should now be a varchar(191) in utf8mb4. That changes the maximum length a column or index can hold. While character sets define the legal characters that can be stored in a column, collations are rules that determine how string comparisons are made. In utf8mb4, we add an extra byte to store special characters like smileys. In utf8, a character can be encoded in a maximum of 3 bytes. NB: a note of warning when migrating from utf8 to utf8mb4. If you don’t care about any of that, simply go with the default, latin1. For that you’ll need utf8mb4, available since MySQL 5.5.3. Be careful, this encoding won’t handle smileys. more parameters can be set (e.g., charset and collation for mysql). If you need to handle special characters, like letters with accents, people will usually tell you to go for a utf8 encoding. client, Database client to create the connection. You’ll find SQL commands at the end of this article to check and modify that. Note that you can set both encoding and collation at the server level, at the database level, at the table level or even for particular columns only. The collation is used when comparing data, for example in a WHERE clause (equal or LIKE), or with unicity constraints on text columns. Here’s a quick guide on how to choose your encoding and the collation right from the start, and avoid the pain of debugging your encoding issues. Then you copy the result and run it as the final SQL command that will do the conversion.You generally start with the defaults and fix issues along the way. What you get is a list of SQL commands to alter the collation and character set of all tables. TABLE_SCHEMA = 'dbase'Īgain, ‘dbase’ is the name of the database to alter. ', tbl.TABLE_NAME, ' CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci ') FROM information_schema. SELECT CONCAT('ALTER TABLE ', tbl.TABLE_SCHEMA, '. The first step is to collect all table names and produce new SQL commands to alter them: You have to execute an SQL command to read all tables and produce the SQL commands that will be used to actually do the job for you! So there is a shortcut although indirect. In the general case, there are far too many tables to do it this way (and still be happy…) Where ‘dbase’ is the name of the database and ‘table’ the name of each table. table CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci So one way to convert to utf8 is to go table by table and type the SQL command:ĪLTER TABLE dbase. Even though all default settings include “utf8-general-ci” every newly created database keeps getting that “swedish” collation and character set! ![]()
0 Comments
Leave a Reply. |