Let's say I have created a MySQL database (in an encapsulated local development environment):
$ mysql -uroot -proot -e "create database FOO"
And imported an SQL dump:
$ mysql -uroot -proot FOO < /var/tmp/BAR.sql
And now I simply re-import a newer dump from the same source:
$ mysql -uroot -proot FOO < /var/tmp/FUBAR.sql
Questions: Is this a reliable method to simply import the newest data? Will existing tables simply be overwritten? As far as I can inspect it seems to be no problem. Or should I always better drop the database first, recreate it and then import the newer dump?
Depends on the dump file. If it has DROP TABLE IF EXISTS and CREATE TABLE statements, it will overwrite tables. But it can also do any other thing SQL allows you to do - alter tables, only insert data, etc.
I see nothing unreliable in that.
Related
So I wanted to format my system and I had a lot of works that I have done on my localhost that involves databases. I followed the normal way of backing up the database by exporting it into an SQL file but I think I made a mess by making a mistake of backing up everything in one SQL file (I mean the whole localhost was exported to just one SQL file).
The problem now is: when I try to import the backed up file I mean the (localhost.sql), I get an error like
tables already exist.
information_schema
performance_schema
an every other tables that comes with Xampp, which has been preventing me from importing the database.
These tables are the phpmyadmin tables that came with Xampp. I have been trying to get past this for days.
My question now is that can I extract different databases from the same compiled SQL database file?
To import a database you can do following things:
mysql -u username -p database_name < /path/to/database.sql
From within mysql:
mysql> use database_name;
mysql> source database.sql;
The error is quite self-explanatory. The tables information_schema and performance_schema are already in the MySQL server instance that you are trying to import to.
Both of these databases are default in MySQL, so it is strange that you would be trying to import these into another MySQL installation. The basic syntax to create a .sql file to import from the command line is:
$ mysqldump -u [username] -p [database name] > sqlfile.sql
Or for multiple databases:
$ mysqldump --databases db1 db2 db3 > sqlfile.sql
Then to import them into another MySQL installation:
$ mysql -u [username] -p [database name] < sqlfile.sql
If the database already exists in MySQL then you need to do:
$ mysqlimport -u [username] -p [database name] sqlfile.sql
This seems to be the command you want to use, however I have never replaced the information_schema or performance_schema databases, so I'm unsure if this will cripple your MySQL installation or not.
So an example would be:
$ mysqldump -uDonglecow -p myDatabase > myDatabase.sql
$ mysql -uDonglecow -p myDatabase < myDatabase.sql
Remember not to provide a password on the command line, as this will be visible in plain text in the command history.
The point the previous responders seem to be missing is that the dump file localhost.sql when fed into mysql using
% mysql -u [username] -p [databasename] < localhost.sql
generates multiple databases so specifying a single databasename on the command line is illogical.
I had this problem and my solution was to not specify [databasename] on the command line and instead run:
% mysql -u [username] -p < localhost.sql
which works.
Actually it doesn't work right away because of previous attempts
which did create some structure inside mysql, and those bits in localhost.sql
make mysql complain because they already exist from the first time around, so
now they can't be created on the second time around.
The solution to THAT is to manually edit localhost.sql with modifications like
INSERT IGNORE for INSERT (so it doesn't re-insert the same stuff, nor complain),
CREATE DATABASE IF NOT EXISTS for CREATE DATABASE,
CREATE TABLE IF NOT EXISTS for CREATE TABLE,
and to delete ALTER TABLE commands entirely if they generate errors because by then
they've already been executed ((and INSERTs and CREATEs perhaps too for the same reasons). You can check the tables with DESCRIBE TABLE and SELECT commands to make sure that the ALTERations, etc. have taken hold, for confidence.
My own localhost.sql file was 300M which my favorite editor emacs complained about, so I had to pull out bits using
% head -n 20000 localhost.sql | tail -n 10000 > 2nd_10k_lines.sql
and go through it 10k lines at a time. It wasn't too hard because drupal was responsible for an enormous amount, the vast majority, of junk in there, and I didn't want to keep any of that, so I could carve away enormous chunks easily.
unzip -p /pathoffile/database_file.zip | mysql -uusername -p databsename;
Best way to import database in localhost has simple 5 steps:
zip sql file first to compress databse size.
go to termianl.
create empty database.
Run Command unzip databse With Import database: unzip -p /pathoffile/database_file.zip | mysql -uusername -p databsename;
Enter Password
I need to restore a dumped database, but without discarding existing rows in tables.
To dump I use:
mysqldump -u root --password --databases mydatabase > C:\mydatabase.sql
To restore I do not use the mysql command, since it will discard all existing rows, but instead mysqlimport should do the trick, obviously. But how? Running:
mysqlimport -u root -p mydatabase c:\mydatabase.sql
says "table mydatabase.mydatabase does not exist". Why does it look for tables? How to restore dump with entire database without discarding existing rows in existing tables? I could dump single tables if mysqlimport wants it.
What to do?
If you are concerned with stomping over existing rows, you need to mysqldump it as follows:
MYSQLDUMP_OPTIONS="--no-create-info --skip-extended-insert"
mysqldump -uroot --ppassword ${MYSQLDUMP_OPTIONS} --databases mydatabase > C:\mydatabase.sql
This will do the following:
remove CREATE TABLE statements and use only INSERTs.
It will INSERT exactly one row at a time. This helps mitigate rows with duplicate keys
With the mysqldump performed in this manner, now you can import like this
mysql -uroot -p --force -Dtargetdb < c:\mydatabase.sql
Give it a Try !!!
WARNING : Dumping with --skip-extended-insert will make the mysqldump really big, but at least you can control each duplicate done one by one. This will also increase the length of time the reload of the mysqldump is done.
I would edit the mydatabase.sql file in a text editor, dropping the lines that reference dropping tables or deleting rows, then manually import the file normally using the mysql command as normal.
mysql -u username -p databasename < mydatabase.sql
The mysqlimport command is designed for dumps created with the mysql command SELECT INTO OUTFILE rather than direct database dumps.
This sounds like it is much more complicated than you are describing.
If you do a backup the way you describe, it has all the records in your database. Then you say that you do not want to delete existing rows from your database and load from the backup? Why? The reason why the backup file (the output from mysqldump) has the drop and create table commands is to ensure that you don't wind up with two copies of your data.
The right answer is to load the mysqldump output file using the mysql client. If you don't want to do that, you'll have to explain why to get a better answer.
I'm using the following command to create an incremental backup in MySQL
mysqldump -uusername -ppassword db_name --flush-logs > D:\dbname_incremental_backup.sql
However the sql file is as big as a complete backup, and obviously importing it takes a long time as well. Could anybody tell me how to create incremental backups and import just the new data from each incremental backup rather than the whole database again?
I have read all the related articles in dev.mysql.com but still can not understand how to do it.
mysqldump only creates full backups. There's no built-in functionality for incremental backups.
For that sort of thing you probably want Percona xtrabackup but that will only work with InnoDB tables. This is usually not an issue since using MyISAM tables is considered extremely harmful.
By default a mysql dump will drop tables making an incremental update impossible. If you open up the resulting file, you will see something like:
DROP TABLE IF EXISTS `some_table_name`;
You can create a dump without dumping and creating new tables using the --no-create-info option. To make your dump friendly to incremental imports, you should also use --skip-extended-import which will break inserts out into one insert statement per row. Combined with using --force on the import will mean that inserts for rows that exist will fail but the import will continue. You will end up seeing errors in the logs for rows that already exist, but new rows will be inserted as desired.
You should be able to export with the following command (I also recommend not typing the password in the command so that it won't appear in your history)
mysqldump -u username -p --no-create-info --skip-extended-insert db_name --flush-logs > D:\dbname_incremental_backup.sql
You can then import with the following command:
mysql -u username -p --force db_name < D:\dbname_incremental_backup.sql
This question already has answers here:
How do I rename a MySQL database (change schema name)?
(46 answers)
Closed 8 years ago.
I created a database with the name of hrms. Now I need to change database name to sunhrm. But, It is disabled in MySQL workbench. Can I do that on the Linux server itself?
In case you need to do that from the command line, just copy, adapt & paste this snippet:
mysql -e "CREATE DATABASE \`new_database\`;"
for table in `mysql -B -N -e "SHOW TABLES;" old_database`
do
mysql -e "RENAME TABLE \`old_database\`.\`$table\` to \`new_database\`.\`$table\`"
done
mysql -e "DROP DATABASE \`old_database\`;"
I don't think you can do this. Basic answers will work in many cases, and in others cause data corruptions. A strategy needs to be chosen based on heuristic analysis of your database. That is the reason this feature was implemented, and then removed. [doc]
You'll need to dump all object types in that database, create the newly named one and then import the dump. If this is a live system you'll need to take it down. If you cannot, then you will need to setup replication from this database to the new one.
If you want to see the commands that could do this, #satishD has the details, which conveys some of the challenges around which you'll need to build a strategy that matches your target database.
It's possible to copy database via mysqldump command without storing dump into file:
mysql -u root -p -e "create database my_new_database"
mysqldump -u root -p original_database | mysql -u root -p my_new_database
mysql -u root -p -e "drop database original_database"
You can create a new database exactly as the previous database existed and then drop the old database when you're done. Use the mysqldump tool to create a .sql backup of the database via mysqldump orig_db > orig_db.sql or if you need to use a username and password then run mysqldump -u root -p orig_db > orig_db.sql. orig_db is the name of the database you want to "rename", root would be the user you're logging in as and orig_db.sql would be the file created containing the backup. Now create a new, empty database with the name you want for the database. For example, mysql -u root -p -e "create database new_db". Once that's done, then run mysql -u root -p new_db < orig_db.sql. new_db now exists as a perfect copy of orig_db. You can then drop the original database as you now have it existing in the new database with the database name you wanted.
The short, quick steps without all the above explanation are:
mysqldump -u root -p original_database > original_database.sql
mysql -u root -p -e "create database my_new_database"
mysql -u root -p my_new_database < original_database.sql
mysql -u root -p -e drop database originl_database
Hope this helps and this is a reliable means to accomplish it without using some ad-hoc method that will corrupt your data and create inconsistencies.
You can do it by RENAME statement for each table in your "current_db" after create the new schema "other_db"
RENAME TABLE current_db.tbl_name TO other_db.tbl_name
Source Rename Table Syntax
In short no. It is generally thought to be too dangerous to rename a database. MySQL had that feature for a bit, but it was removed. You would be better off using the workbench to export both the schema and data to SQL then changing the CREATE DATABASE name there before you run/import it.
I used following method to rename the database
take backup of the file using mysqldump or any DB tool eg heidiSQL,mysql administrator etc
Open back up (eg backupfile.sql) file in some text editor.
Search and replace the database name and save file.
Restore the edited SQL file
If your DB contains only MyISAM tables (do not use this method if you have InnoDB tables):
shut down the MySQL server
go to the mysql data directory and rename the database directory (Note: non-alpha characters need to be encoded in a special way)
restart the server
adjust privileges if needed (grant access to the new DB name)
You can script it all in one command so that downtime is just a second or two.
For impatient mysql users (like me), the solution is:
/etc/init.d/mysql stop
mv /var/lib/mysql/old_database /var/lib/mysql/new_database
/etc/init.d/mysql start
First backup the old database called HRMS and edit the script file with replace the word HRMS to SUNHRM. After this step import the database file to the mysql
Another way to rename the database or taking image of the database is by using Reverse engineering option in the database tab. It will create a ERR diagram for the database. Rename the schema there.
after that go to file menu and go to export and forward engineer the database.
Then you can import the database.
Hi I use mysql administrator and have restored backup files (backup.sql). I would like to use restore the structure without data and it is not giving me an option to do so. I understand phpadmin provides this. I can not use this however. Any one can tell me an easy way?
Dump database structure only:
cat backup.sql | grep -v ^INSERT | mysql -u $USER -p
This will execute everything in the backup.sql file except the INSERT lines that would have populated the tables. After running this you should have your full table structure along with any stored procedures / views / etc. that were in the original databse, but your tables will all be empty.
You can change the ENGINE to BLACKHOLE in the dump using sed
cat backup.sql | sed 's/ENGINE=(MYISAM|INNODB)/ENGINE=BLACKHOLE/g' > backup2.sql
This engine will just "swallow" the INSERT statements and the tables will remain empty. Of course you must change the ENGINE again using:
ALTER TABLE `mytable` ENGINE=MYISAM;
IIRC the backup.sql files (if created by mysqldump) are just SQL commands in a text file. Just copy-paste all the "create ..." statements from the beginning of the file, but not the "insert" statements in to another file and "mysql < newfile" you should have the empty database without any data in it.
there is no way to tell the mysql client to skip the INSERT commands. the least-hassle way to do this is run the script as-is and let it load the data, then just TRUNCATE all of the tables.
you can write a script to do the following:
1 : import the dump into a new database.
2 : truncate all the tables with a loop.
3 : export the db again.
4 : now u just have the structure
You can backup you MYSQL database structure with
mysqldump -u username –p -d database_name > backup.sql
(You should not supply password at command line as it leads to security risks.MYSQL will ask for password by default.)