I have a table called TableA in DatabaseA and I want to create the same TableA in DatabaseB. I am able to do so but copying only the structure and the data, I seem unable to also create the primary keys and indexes. Is there an SQL statement I can use that copies the table structure, the table data, the primary keys and indexes please?
I am using Oracle 11G.
1. First Method
To get tables and indexes without data see following post
Stack Post
after creating table you can load data using
insert into dest_table as select * from source_table
2. Second Method
use expdp to take backup of source table using table=yourtable parameter as this will by default will take indexes and when you will import using impdp on destination database it will automatically rebuild those indexes.
Related
I have done some queries in a read-only (Oracle/SQL developer) dB where I have absolutely no privileges to create temporary tables or anything else. I want to export the tables resulting of my queries into another db (PostGre/pgAdmin) db in order to be able to do other queries on the result.
Is there an easy way to create the columns of my exported tables in the PostGre db using pgAdmin or do I have to create all the columns manually ?
You could install the Oracle Foreign Data Wrapper in your PostgreSQL database and use IMPORT FOREIGN SCHEMA to create foreign tables for your Oracle tables.
Then you can use
CREATE TABLE local_table AS SELECT * FROM foreign_table;
to copy the data.
I have an existing DB2 database and a table named
employee with columns
id,e_name,e_mobile_no,e_dob,e_address.
How can I add a new column e_father_name before e_mobile_no?
You should try using the ADMIN_MOVE_TABLE procedure which allows to change the table structure.
The ALTER TABLE only allows adding columns to the end of the table. The reason is that it would change the physical structure of the table, i.e., each row would need to be adapted to the new format. This would be quite expensive.
Using the mentioned procedure ADMIN_MOVE_TABLE you would copy the entire table and during that process change the table structure. It requires a significant amount of space and time.
In DB2 IBM i v7r1 you can do it, try on your DB2 version
alter table yourtable
add column e_father_name varchar(10) before e_mobile_no
I always do the following --
Take a backup/dump of table data and db2look
(If you dump to a CSV file as I do I suggest dumping in the new format so for example put null for the new column in the right place.
Drop table and indexes
Create table with the new colunn
Load data with old values
Recreate all indexes and runstats.
Once you have done it a few times it becomes old hat.
I found this link that could be the solution to my question, but I need some clarification.
I have two DBs on one server, the one DB is a backup. I have a broken table and want to replace the table values/records with the table from the backup DB. Can I use the method from the link above, or is it only if the destination table is empty that I can use the "INSERT INTO destination"?
My goal is to overwrite the table with the backup values.
Since your goal is to replace the entire table with the table from the backup database, you can TRUNCATE the target table and then reload from the backup table using INSERT...SELECT.
You will need to be mindful of foreign key constraints. TRUNCATE is not allowed if FKs reference the table so you will need to use DELETE to empty the table instead.
Is it possible to copy a table (with definition, constraints, identity) to a new table?
Generate a CREATE script based on the table
Modify the script to create a different table name
Perform an INSERT from selecting everything from the source table
No, not really, you have to script it out, then change the names
you can do this
select * into NewTable
FROM OldTable
WHERE 1 =2 --if you only want the table without data
but it won't copy any constraints
It's not the most elegant solution, but you could use a tool like the free Database Publishing Wizard from Microsoft.
It creates an SQL script of the table definition including data and including indexes and stuff. But you would have to alter the script manually to change the table name...
Another possibility:
I just found this old answer on SO.
This script is an example to script the constraints of all tables, but you can easily change it to select only the constraints of "your" table.
So, you could do the following:
Create the new table with data like SQLMenace said (select * into NewTable from OldTable)
Add constraints, indexes and stuff by changing this SQL script
I am migrating an MS Access application (which has linked tables to a MSSQL Server) to MySQL.
As a means to overcome some MSAccess table naming problems, I am seeking a solution to add a MySQL table alias that will point to an existing table in the MySQL database. Ideally I would like to create the alias 'dbo_customers' in mysql that would point to the customers table also in mysql.
To be clear I am not wanting to alias a table name inside a query like this:
SELECT * FROM customers AS dbo_customers
But rather I would like to be able issue the following query:
SELECT * FROM dbo_customers
and have it return data from the customers table.
Off the top of my head
CREATE VIEW dbo_customers AS
SELECT * FROM customers
Maybe not the best solution but should work as the view is updatable. Will definitely work for Read Only
You can create a View.
CREATE VIEW dbo_customers AS SELECT * FROM customers;
If that doesn't work for you, you could try creating a shadow-copy of the table, and use Triggers to keep the tables synced.
For example:
CREATE TABLE t1( id serial primary key, field varchar(255) not null );
CREATE TABLE dbo_t1( id serial primary key, field varchar(255) not null );
-- INSERT trigger
CREATE TRIGGER t1_dbo_insert AFTER INSERT ON t1
FOR EACH ROW BEGIN
INSERT INTO dbo_t1 SET field = NEW.field;
-- No need to specify the ID, it should stay in-sync
END
-- UPDATE trigger
CREATE TRIGGER t1_dbo_update AFTER UPDATE ON t1
FOR EACH ROW BEGIN
UPDATE dbo_t1 SET field = NEW.field WHERE id = NEW.id;
END
-- DELETE trigger
CREATE TRIGGER t1_dbo_delete AFTER DELETE ON t1
FOR EACH ROW BEGIN
DELETE FROM dbo_t1 WHERE id = OLD.id;
END
Not exactly an 'alias', and far from perfect. But it is an option if all else fails.
there is a simpler solution for MySQL via MERGE table engine:
imagine we have table named rus_vacancies and need its English equivalent
create table eng_vacancies select * from rus_vacancies;
delete from eng_vacancies;
alter table eng_vacancies ENGINE=MERGE;
alter table eng_vacancies UNION=(rus_vacancies);
now table rus_vacancies equals to table eng_vacancies for any read-write operations
one limitation - original table must have ENGINE=MyISAM (it can be easily done by "alter table rus_vacancies ENGINE=MyISAM")
You could create a view named dbo_customers which is backed by the customers table.
#OMG Ponies ponies said in a comment:
Why not rename the table?
...and it seems the obvious answer to me.
If you create an ODBC linked table for the MySQL table customers it will be called customers and then all you have to do is rename the table to dbo_customers. There is absolutely no need that I can see to create a view in MySQL for this purpose.
That said, I'd hate to have an Access app that was using SQL Server table names when the MySQL tables were not named the same thing -- that's just confusing and will lead to maintenance problems (i.e., it's simpler for the linked tables in the Access front end to have the same names as the MySQL tables, wherever possible). If I were in your position, I'd get a search and replace utility and replace all the SQL Server table names with the MySQL table names throughout the entire Access front end. You'd likely have to do it one table at a time, but in my opinion, the time it takes to do this now is going to be more than made up for in clarity going forward with development of the Access front end.
I always rename my "linked to SQL" tables in Access from
{dbo_NAME} to {NAME}.
The link creates the table name as {dbo_NAME} but access occasionally has problems with the dbo_ prefix.
Aliases would be nice, yet MySQL does NOT have such a feature.
One option that may serve your needs, besides creating a view, is to use the FEDERATED storage engine locally.
CREATE TABLE dbo_customers (
id INT(20) NOT NULL AUTO_INCREMENT,
name VARCHAR(32) NOT NULL DEFAULT '',
PRIMARY KEY (id),
)
ENGINE=FEDERATED
DEFAULT CHARSET=latin1
CONNECTION='mysql://fed_user#localhost:9306/federated/customers';
There are currently some limitations with the FEDERATED storage engine. Here are a couple especially important ones:
FEDERATED tables do not support transactions
FEDERATED tables do not work with the query cache
I'd like to mention a bad solution I explored (and abandoned), which was to use hardlinks on the .frm, .MYD and .MYI files corresponding to my table in /var/lib/mysql/{name_of_my_database}/.
It does, however, NOT work. For InnoDB tables, it simply cannot (even if you hardlink the .idb file) because tables are also referenced in ibdata1.
For MyISAM tables, it kind of works, except it doesn't because in memory, the tables are still distinct and thus do not share cache. So if you write a row to original_table, it won't immediately appear in aliased_table. You would have to flush tables first… which defeats the purpose and even causes data loss (if you insert a row in both the original and the alias before flushing, only one row is kept).
I thought my experiment was worth mentioning as a cautionary tale.