i tried to insert arabic word in MySql and it got inserted and when i displayed it it was there
but there was a warning 3720
for context here is the table:
create table SIGHTS ( S_no int not null PRIMARY KEY, S_name Nvarchar(30) not null);
and here is the inserted value:
insert into SIGHTS values (1,(N'كهف الهكبة'));
so? is it safe to ignore the warning or what should i do with it ?
it seems like you have used the default CHARACTER SET "utf8mb4" and the COLLATE utf8mb4_0900_ai_ci when you create the database. for more information, check this link out
when you create the database using the default "create" statement, which is
CREATE DATABASE _dbase;
it will execute the following statement adding the default CHARACTER SET
CREATE DATABASE _dbase CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci;
change the CHARACTER SET to "utf8" and the COLLATE to "utf8_general_ci" or "utf8_unicode_ci", you need to use the following statements :
CREATE DATABASE _dbase CHARACTER SET utf8 COLLATE utf8_general_ci;
or
CREATE DATABASE _dbase CHARACTER SET utf8 COLLATE utf8_unicode_ci;
Related
Hello I'm trying to convert my database, one table and field to utf using this script
-- Write a script that converts hbtn_0c_0 database to UTF8
-- (utf8mb4, collate utf8mb4_unicode_ci) in your MySQL server.
-- You need to convert all of the following to UTF8:
-- Database hbtn_0c_0
-- Table first_table
-- Field name in first_table
ALTER DATABASE
`hbtn_0c_0`
CHARACTER SET utf8mb4
COLLATE utf8mb4_unicode_ci;
USE `hbtn_0c_0`;
ALTER TABLE
`first_table`
CONVERT TO CHARACTER SET utf8mb4
COLLATE utf8mb4_unicode_ci;
ALTER TABLE
`first_table`
CHANGE `name`
VARCHAR(256)
CHARACTER SET utf8mb4
COLLATE utf8mb4_unicode_ci;
But I have a SQL error. Please help me
black_genius#genius:~/Documents/ALX_Task/alx-higher_level_programming/0x0D-SQL_introduction$ cat 100-move_to_utf8.sql | mysql -hlocalhost -uroot -p
Enter password:
ERROR 1064 (42000) at line 22: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'VARCHAR(256)
CHARACTER SET utf8mb4
COLLATE utf8mb4_unicode_ci' at line 4
I'm using mysql version v8.0.31 on ubuntu 22.10
When you change a column, you need to provide the old name and the new name, even if the name is the same. See the syntax in the documentation:
CHANGE [COLUMN] old_col_name new_col_name column_definition
In your case it should be
ALTER TABLE
`first_table`
CHANGE `name` `name`
VARCHAR(256)
CHARACTER SET utf8mb4
COLLATE utf8mb4_unicode_ci;
Demonstration: . db-fiddle.com/f/qFuvFqP5PEGbsc8F8DfiaN/0
You don't need to change the individual column if you use ALTER TABLE ... CONVERT TO CHARACTER SET .... That ALTER TABLE automatically converts all string-based columns.
The documentation describes:
To change the table default character set and all character columns
(CHAR, VARCHAR, TEXT) to a new character set, use a statement like
this:
ALTER TABLE tbl_name CONVERT TO CHARACTER SET charset_name;
The statement also changes the collation of all character columns.
Paul Spiegel's answer about the CHANGE COLUMN syntax is correct; that syntax allows you to change a column's name, so you need to specify the column name twice.
An alternative is to use MODIFY COLUMN instead of CHANGE COLUMN. This allows you to change the column type and options, including character set, but not to change the column name. So there's no need to include the column name twice.
ALTER TABLE
`first_table`
MODIFY `name`
VARCHAR(256)
CHARACTER SET utf8mb4
COLLATE utf8mb4_unicode_ci;
But again, in your example, there's no need to use either CHANGE COLUMN or MODIFY COLUMN. The character set conversion should be achieved by using the CONVERT TO CHARACTER SET action.
Here is quetions about adding comment to column for MySQL. Can this comment be utf-8? Also what encoding MySQL uses for these columns by default?
Default character set and collation is set when the database is created
CREATE DATABASE mydb
DEFAULT CHARACTER SET utf8
DEFAULT COLLATE utf8_general_ci;
You can modify character set on a specific column like this
ALTER TABLE t MODIFY col1 CHAR(50) CHARACTER SET utf8;
I've always been surprised that MySQL and related tools tend to specify both CHARACTER SET and COLLATION in CREATE TABLE AND ALTER TABLE statements:
SHOW CREATE TABLE test;
CREATE TABLE ...
ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;
When I select a collation for a column in MySQL Workbench, I get:
ALTER TABLE ...
CHARACTER SET 'latin1' COLLATE 'latin1_general_ci' ...;
I've always supposed that specifying the character set and the collation was redundant, as the collation implies the character set.
Am I wrong?
When I try to mix a collation with another charset, I get an error:
CREATE TABLE ... DEFAULT CHARACTER SET utf8 collate latin1_bin;
COLLATION 'latin1_bin' is not valid for CHARACTER SET 'utf8'
Is it safe to only ever specify the collation?
If so, why do all these tools systematically include the charset in the statement, too?
You are not required to specify character set when creating table, it's automatically set on collate as it described in the MySQL Reference Manual:
MySQL chooses the table character set and collation in the following
manner:
If both CHARACTER SET charset_name and COLLATE collation_name are specified, character set charset_name and collation collation_name are used.
If CHARACTER SET charset_name is specified without COLLATE, character set charset_name and its default collation are used. To see the default collation for each character set, use the SHOW CHARACTER SET statement or query the INFORMATION_SCHEMA CHARACTER_SETS table.
If COLLATE collation_name is specified without CHARACTER SET, the character set associated with collation_name and collation collation_name are used.
Otherwise (neither CHARACTER SET nor COLLATE is specified), the database character set and collation are used.
The table character set and collation are used as default values
for column definitions if the column character set and collation are
not specified in individual column definitions. The table character
set and collation are MySQL extensions; there are no such things
in standard SQL.
So you can create a table using this query:
CREATE TABLE `tabletest` (
`id` int(11) unsigned NOT NULL AUTO_INCREMENT,
`name` varchar(255) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1 COLLATE=latin1_general_ci;
This query will create a table with CHARSET=latin1 COLLATE=latin1_general_ci, so it's safe to specify COLLATE only.
As for why are there both CHARSET and COLLATE, please read the following:
What is the difference between collation and character set?
When creating a MySQL database with CREATE SCHEMA, it uses MySQL's default character set and collation. But I want to change that.
How do I create a MySQL Database with a specific character set and collation?
You can try like this:
CREATE DATABASE IF NOT EXISTS someDatabase
DEFAULT CHARACTER SET = 'utf8' DEFAULT COLLATE 'utf8_general_ci'
and if the database is already created, then you can alter is like this:
ALTER DATABASE databasename CHARACTER SET utf8 COLLATE utf8_unicode_ci;
CREATE SCHEMA `my_database`
DEFAULT CHARACTER SET utf8
COLLATE utf8_unicode_ci ;
Ok, in the existing table,
CREATE TABLE tb(id int, `text` varchar(255) character set latin1 collate latin1_bin default NULL)ENGINE=InnoDB DEFAULT CHARSET=latin1
I want to make the text column to be utf8 and it supports Case Sensitive for select query
Suppose there is "ã" & "Ã" which is utf8 in the text column
id - text
1 - ã
2 - Ã
, and when user select * from tb where text='Ã'it should show record with id=2 only
Is this query the correct one
alter table tb modify column text varchar(255) character set utf8 collate utf8_general_ci default NULL
I have no idea what utf8_general_ci means? am i doing cortrectly?
This can be done by using the Alter Command.
Like ALTER TABLE urtable MODIFY col1 VARCHAR(50) CHARACTER SET utf8;
See column charset conversion here
this is the correct one
alter table tb modify text varchar(255) character set utf8 collate utf8_bin default NULL