I got two schema A and B. In A there is a table 'company' and in B there is a table 'newcompany'. Now I need all the data which is residing on A.company to be updated on B.newcompany whenever there is some data updation on A.company.
Please help me out with a query or some function which implements this functionality.
You could give grants to the user and simply access the table as B.newcompany inside an onupdate trigger for the A.company table.
Related
I am working on such application where table audit should perform to make revision of updated records. Let's say for example I have to log each field update in Users update.
I wants to create clone of existing user table by
CREATE TABLE users_audit LIKE users;
My main question is,
Is there any alternative way or provision in Laravel migration to create table from existing table ?
I know we can run raw sql query in migration up/down method using \DB::raw();
But it would be helpful if any helper function available to create table from existing table like, create or table
Yes, you can, see the below link
Click this link
This statement is used to execute raw queries
DB::statement('CREATE TABLE tablename LIKE existingtablename');
I have the following scenario and need to solve it in ORACLE:
Table A is on a DB-server
Table B is on a different server
Table A will be populated with data.
Whenever something is inserted to Table A, i want to copy it to Table B.
Table B nearly has similar columns, but sometimes I just want to get
the content from 2 columns from tableA and concatenate it and save it to
Table B.
I am not very familiar with ORACLE, but after researching on GOOGLE
some say that you can do it with TRIGGERS or VIEWS, how would you do it?
So in general, there is a table which will be populated and its content
should be copien to a different table.
This is the solution I came up so far
create public database link
other_db
connect to
user
identified by
pw
using 'tns-entry';
CREATE TRIGGER modify_remote_my_table
AFTER INSERT ON my_table
BEGIN INSERT INTO ....?
END;
/
How can I select the latest row that was inserted?
If the databases of these two tables are in two different servers, then you will need a database link (db-link) to be created in Table A schema so that it can access(read/write) the Table B data using db-link.
Step 1: Create a database link in Table A server db pointing to Table B server DB
Step 2: Create a trigger for Table A, which helps in inserting data to the table B using database link. You can customize ( concatenate the values) inside the trigger before inserting it into table B.
This link should help you
http://searchoracle.techtarget.com/tip/How-to-create-a-database-link-in-Oracle
Yes you can do this with triggers. But there may be a few disadvantages.
What if database B is not available? -> Exception handling in you trigger.
What if database B was not available for 2h? You inserted data into database A which is now missing in database B. -> Do crazy things with temporarily inserting it into a cache table in database A.
Performance. Well, the performance for inserting a lot of data will be ugly. Each time you insert data, Oracle will start the PL/SQL engine to insert the data into the remote database.
Maybe you could think about using MViews (Materialized Views) to replicate the data via database link. Later you can build your queries so that they access tables from database B and add the required data from database A by joining the MViews.
You can also use fast refresh to replicate the data (almost) realtime.
From perspective of an Oracle Database Admin this would make a lot more sense than the trigger approach.
try this code
database links are considered rather insecure and oracle own options are having licences associated these days, some of the other options are deprecated as well.
https://gist.github.com/anonymous/e3051239ba401e416565cdd912e0de8c
uses ora_rowscn to sync tables across two different oracle databases.
I have a table cars with attributes: id, name. I also have another table specs with id, car_id, name. This tables are related with one to many relations from the Models. I also have set up the foreign keys in.
I have a controller manageData where i have a function insertCar which i use to insert data and update both tables. I wan to create another function deleteCar from where i can delete the car along with its specs from the other table
Use onDelete() method in migration when defining foreign key:
$table->foreign('car_id')->references('id')->on('cars')->onDelete('cascade');
In this case when you'll delete a car record, related data will be automatically deleted from another table.
https://laravel.com/docs/5.4/migrations#foreign-key-constraints
I'm wondering if its possible to create a view that automatically checks if there is a new monthly created table and if there is include that one?
We have a new table created each month and each one ends with the number of the month, like
table for January: table_1
table for February: table_2
etc...
Is it possible to create a view that takes data from all those tables and also finds when there is a new one created?
No, a view's definition is static. You would have to replace the view each month with a new copy that included the new table; you could write a dynamic PL/SQL program to do this. Or you could create all the empty tables now and include them all in the view definition; if necessary you could postpone granting any INSERT access to the future tables until they become "live".
But really, this model is flawed - see Michael Pakhantsov's answer for a better alternative - or just have one simple table with a MONTH column.
Will be possible if you instead of creating new table each month will create new partition for existing table.
UPDATE:
If you have oracle SE without partitioning option you can create two tables: LiveTable and ArchiveTable. Then each month you need move rows from Live to ArchiveTable and clean live table. In this case you need create view just from two tables.
Another option is to create the tables in another schema with grants to the relevant user and create public synonyms to them.
As the monthly tables get created in the local schema, they'll "out-precedence" the public synonyms and the view will pick them up. It will still get invalidated and need recompiling, but the actual view text should need changing, which may be simpler from a code-control point of view.
You can write a procedure or function that looks at USER_TABLES or ALL_TABLES to determine if a table exists, generate dynamic sql, and return a ref cursor with the data. The same can be done with a pipelined function.
I have a view that is built on multiple tables from different users schema. By virtue of the currently logged in user, he is able to see the table from different schema. When the view is created the table name becomes ambiguous as the user have access to the same tables from the different schema.
Is there any way to specify to use the table from current user schema while creating the view?
Can we do it for one of the tables from the view definition while other tables can be selected from any schema?
"When the view is created the table
name becomes ambiguous as the user
have access to the same tables from
the different schema"
It isn't ambiguous to Oracle.
The view exists in a schema, SCHEMA_1. If that view refers to an object TABLE_A, Oracle will first look for an object TABLE_A in SCHEMA_1. If it finds a table, it will use that. If it finds a SYNONYM it will use whatever the synonym points to. If there is nothing in SCHEMA_1, it will look for a PUBLIC SYNONYM for TABLE_A and use whatever that points to.
SYNONYMS can point to other synonyms, views or tables.
You can query USER_DEPENDENCIES to see what objects the view is actually based on.
You cannot have a view in SCHEMA_1 that uses TABLE_A in SCHEMA_2 if queried from SCHEMA_2 but uses a different TABLE_A in SCHEMA_3 if queried from SCHEMA_3.
You should be able to access schema (with correct permissions) by prefixing the schema name.
schemaname.tablename
Hope I understood your question correctly.