For InnoDB, the following seems to work: create the new empty database, then rename each table in turn into the new database:
RENAME TABLE old_db.table TO new_db.table;
You will need to adjust the permissions after that.
For scripting in a shell, you can use either of the following:
mysql -u username -ppassword old_db -sNe 'show tables' | while read table; \
do mysql -u username -ppassword -sNe "rename table old_db.$table to new_db.$table"; done
OR
for table in `mysql -u root -ppassword -s -N -e "use old_db;show tables from old_db;"`; do mysql -u root -ppassword -s -N -e "use old_db;rename table old_db.$table to new_db.$table;"; done;
Notes:
- There is no space between the option
-p
and the password. If your database has no password, remove the -u username -ppassword
part.
If some table has a trigger, it cannot be moved to another database using above method (will result Trigger in wrong schema
error). If that is the case, use a traditional way to clone a database and then drop the old one:
mysqldump old_db | mysql new_db
If you have stored procedures, you can copy them afterwards:
mysqldump -R old_db | mysql new_db
You can use GROUP_CONCAT
:
SELECT person_id,
GROUP_CONCAT(hobbies SEPARATOR ', ')
FROM peoples_hobbies
GROUP BY person_id;
As Ludwig stated in his comment, you can add the DISTINCT
operator to avoid duplicates:
SELECT person_id,
GROUP_CONCAT(DISTINCT hobbies SEPARATOR ', ')
FROM peoples_hobbies
GROUP BY person_id;
As Jan stated in their comment, you can also sort the values before imploding it using ORDER BY
:
SELECT person_id,
GROUP_CONCAT(hobbies ORDER BY hobbies ASC SEPARATOR ', ')
FROM peoples_hobbies
GROUP BY person_id;
As Dag stated in his comment, there is a 1024 byte limit on the result. To solve this, run this query before your query:
SET group_concat_max_len = 2048;
Of course, you can change 2048
according to your needs. To calculate and assign the value:
SET group_concat_max_len = CAST(
(SELECT SUM(LENGTH(hobbies)) + COUNT(*) * LENGTH(', ')
FROM peoples_hobbies
GROUP BY person_id) AS UNSIGNED);
Best Answer
Try this to create the user:
Try this to give it access to the database
dbTest
:If you are running the code/site accessing MySQL on the same machine, hostname would be localhost.
Now, the break down.
GRANT
- This is the command used to create users and grant rights to databases, tables, etc.ALL PRIVILEGES
- This tells it the user will have all standard privileges. This does not include the privilege to use the GRANT command however.dbtest.*
- This instructions MySQL to apply these rights for use in the entire dbtest database. You can replace the * with specific table names or store routines if you wish.TO 'user'@'hostname'
- 'user' is the username of the user account you are creating. Note: You must have the single quotes in there. 'hostname' tells MySQL what hosts the user can connect from. If you only want it from the same machine, uselocalhost
IDENTIFIED BY 'password'
- As you would have guessed, this sets the password for that user.