I have a database, and a set of tables. The scenario is that, two different departments use the exact same table structure and the server code/frontend, but the data for the departments is completely different.
The best thing would be to have two different databases, with the exact structure and different data.
However, if I would try to implement this in just 1 database, would it be possible? I cannot change the table names, as it would require changing the entire code which queries the tables. Is there any way to create sub-folders/directories in a single database?
I searched, and there probably isn't. But maybe there is a workaround someone can suggest?
Read about Identifier Qualifiers. You can have tables of the same name only if they are in separate databases, and you use the database name as a qualifier.
SELECT * FROM db1.sametablename;
SELECT * FROM db2.sametablename;
You can join tables across databases in the same query:
SELECT * FROM db1.sametablename JOIN db2.sametablename;
You can even declare foreign key constraints across databases:
ALTER TABLE db1.sametablename ADD FOREIGN KEY (col1)
REFERENCES db2.sametablename (col1);
Databases are basically a namespace for tables and other objects.
Stop the Mysql Server and restart it again, This must solve the issue.
Windows
mysqladmin -u root -p shutdown
Linux
/etc/init.d/mysqld stop or service mysqld stop or service mysql stop
Related
Wondering if there is a way to skip / ignore all temp tables using mysqldump. In our instance, these tables are prefixed as tmp{guid}.
These temp tables have a very short lifespan, they are used for building some sort of reports in its parent application. Lifetime may be up to 1 minute.
EDIT:
It has been suggested that I use the ignore-tables parameter, unfortunately this doesn't provide a way for me to specify a wildcard as the table name (tmp*).
You are not talking about tables from CREATE TEMPORARY TABLE ..., correct? Instead, you are talking about a set of tables with a particular naming convention?
Instead of trying to do it with table names, do it with a DATABASE:
CREATE TABLE TempTables;
CREATE TABLE TempTables.abcd (...);
And reference them via the db name:
INSERT INTO TempTables.abcd ...
SELECT ... FROM TempTables.abcd JOIN ...
Then use the suitable parameters on mysqldump to avoid that oneDATABASE` (or pick all the other databases to dump).
I'm using MySQL.
I have a "customers" table in database A (located on server).
I want to add them to the customer table in database B (located on localhost) without deleting anything.
I'm very new to SQL commands or MySQL in general so try to be the most explanatory as you can.
If you need more information about something I will edit the post and add it.
(I have MySQL workbench)
Thanks.
On server (DB A):
# Sets our database as default, so we wont have to write `database`.`table` in the consecutive queries.
# Replace *database* with your database name.
USE *database*;
# Makes a copy of the customers table - named customers_export.
# This copy contains all the fields and rows from the original table (without indexes),
# and if you want, you can add a WHERE clause to filter out some data
CREATE TABLE `customers_export` SELECT * FROM `customers`;
Since you are using mysql_workbench, Do a Data Export (in MANAGEMENT section) by choosing the relevant database and only the customers_export table.
On localhost (DB B):
Assuming the database name is the same (otherwise you will need to change the database name in the dump file), do a Data Import/Restore by selecting the dump file which we exported in the previous step.
This will create the customer_export table.
# Set as default
USE *database*;
# If the data you want to import contains *NO* collisions (same primary or unique values in both tables), the structure and table name is the same
INSERT INTO `customers` SELECT * FROM `customers_export`;
And we are done.
If it does have collisions, or you want to play change the column names, some values and etc - you will need to either modify the select statement or update the customers_export table to suit your needs.
Also, back up the customers table on the second server - in case something goes wrong with the insert.
Finally - drop the customers_export table on both servers.
Just use this on localhost:
mysqldump -u YOUR_DATABASE_USER -p YOUR_DATABASE_PASS -h YOUR_SERVER_IP databaseA customers > customer.sql
mysql -u YOUR_DATABASE_USER -p YOUR_DATABASE_PASS databaseB < customer.sql
PD: If want some explanation just tell me
I have a mysql table y in database xxx which I attempted to change compression type before using
alter table y row_format=compressed key_block_size=8
the process stopped half way. I removed temp file '#sql-ib265.frm and #sql-ib265' in mysql lib directory and restarted the server. However
Now when I attempt the alter table y (with the same command above) again I get error.
ERROR 1050 (42S01) at line 1: Table 'xxx/#sql-ib265' already exists
I can't drop table 'xxx/#sql-ib265' because it can't be found.
what should I do?
Edit
Solution:
I ended up dropping the old database and recreate the database.
Try to restart mysql client with the --skip-auto-rehash option and try DROP TABLE again.
If above does not work, try this from MySQL Manual:
You have a corrupt innodb data dictionary..
https://dev.mysql.com/doc/refman/5.0/en/innodb-troubleshooting-datadict.html
Problem with Temporary Table
If MySQL crashes in the middle of an ALTER TABLE operation, you may end up with an orphaned temporary table inside the InnoDB tablespace. Using the Table Monitor, you can see listed a table with a name that begins with #sql-. You can perform SQL statements on tables whose name contains the character “#” if you enclose the name within backticks. Thus, you can drop such an orphaned table like any other orphaned table using the method described earlier. To copy or rename a file in the Unix shell, you need to put the file name in double quotation marks if the file name contains “#”.
There are two ways to fix this problem.
As other answer suggests, official MySQL documentation suggests to drop a specially crafted table. But please note in versions >= 5.1 you need to prefix table name with #mysql50#.
Move (use RENAME TO) all good tables to a temporary database, drop&recreate the original one and then move the tables back. See a blog post for details.
in additional I'm loging in with root to do the recover job but failed. then i chown the .frm file to meet the owner of mysql service and succeed.
For anyone still facing this problem, I have just followed the following steps to solve it, which (to me at least) seem far less daunting than other solutions:
Use mysqldump to back up the database with all its data.
Drop and recreate the database.
Reload the database and all its schema from the file generated in (1).
Because the orphaned tables are hidden anyway, they don't get backed up, so you end up with a database without them. I had all my procedures/functions scripted out anyway, so was able to restore them easily - if you don't, make sure you use the --routines parameter to dump those too.
My dump file was around 1.5GB for the database in question (so it's not small), and the whole thing was completed in a few minutes.
I had the same error. I fixed it by switching the order in which I dropped the tables at the beginning of the file:
DROP TABLE IF EXISTS table_name;
This line is repeated for each table. Tables with foreign keys need to be deleted before the tables with the primary keys to which they point.
I want to replicate certain table from one database into another database in the same server. This tables contain exactly the same fields.
I was considering to use MySQL Replication to replicate that table but some people said that it will increase IO so i find another way to create 3 Trigger (Insert, update and Delete) that will perform exactly the same thing like what i expect.
My Question is, which way is better? Is it using MySQL replication is better even though it's in the same server or using Trigger to replicate the data is better.
Thanks.
I don't know what is your goal, but I got mine getting use of the VIEW functionality.
I had two different applications with separate databases but in the same Mysql server. Application2 needed to get a few data from Application1. In general, this is a trivial situation that you can handle with USE DB1; or USE DB2; as your needing, but my programming framework does not work very well with multiple DBs.
So, lets see my solution...
Here is my select query to retrieve this data:
SELECT id, name FROM DB1.customers;
So, using DB2 as default schema, I've created a VIEW:
USE DB2;
CREATE VIEW app1_customers AS SELECT id, name FROM DB1.customers;
Now I can retrieve this data in DB2 as a regular table with a regular SELECT statement.
SELECT * FROM DB2.app1_customers;
Hope ts useful. BR
Assuming you have two databases on the same server i.e DB1 and DB2 and the table is called tbl1 and it is sitting in DB1 you can query the table like this:
USE DB1;
SELECT * FROM tbl1;
USE DB2;
SELECT * FROM DB1.tbl1;
This way you wont need to copy the data and worry about extra space and extra code. You can query a table in another database on the same server. Replication and triggers are not your answer here. You could also create a view to encapsulate the SQL statement.
Definitely triggers is the way to go. Having another server (slave) will need to spare several MB for installation, logs, cpu and memory usage.
I'd use triggers to keep both tables equal. If you want to create a table with the same columns definition and data use:
USE db2;
CREATE TABLE t1 AS SELECT * FROM db1.t1;
After that, go ahead and create the triggers for Update, Insert and Delete statemetns.
Also you could ALTER the new table to a different engine like MEMORY or add indexes to see if you can improve something.
I'm trying come up with the best method of synchronizing particular rows of 2 different database tables. So, for example there's 2 product tables in different databases as such...
Origin Database
product{
merchant_id,
product_id,
... additional fields
}
Destination Database
product{
merchant_id
product_id
... additional fields
}
So, the database schema is the same for both. However I'm looking to select records with a particular merchant_id, remove all records from the destination table that have that merchant_id and replace those records with records from the origin database of the same merchant_id.
My first thought was using mysqldump, parsing out the create table statements, and only running the Insert Statements. Seems like a pain though. So I was wondering if there is a better technique to do this.
I would think mysql has some method of creating INSERT statements as output from a SELECT statement, so you can define how to insert specific record information into a new db.
Any help would be appreciated, thank you much.
phpMyAdmin has part of this capability: You can run a query and then export the results of that query into a file containing CREATE statements.
Update: And mysqldump has it too: Link
mysqldump -u username -p --where="id='merchant_id'" databasename
In regards to replacing merchant IDs, that part I don't entirely understand yet. You may be better off doing a manual search+replace on them. Can you make a real life example of two such records?