I want to create a table (lets say table_copy) which has same columns as other table (lets call it table_original) in Oracle database, so the query will be like this :
create table table_copy as (select * from table_original where 1=0);
This will create a table, but the constraints of table_original are not copied to table_copy, so what should be done in this case?
Only NOT NULL constraints are copied using Create Table As Syntax (CTAS). Others should be created manually.
You might however query data dictionary view to see the definitions of constraints and implement them on your new table using PL/SQL.
The other tool that might be helpful is Oracle Data Pump. You could import the table using REMAP_TABLE option specifying the name for the new table.
Use a database tool to extract the DDL needed for the constraints (SQL Developer does the job). Edit the resulting script to match the name of the new class.
Execute the script.
If you need to do this programmatically you can use a statement like this:
DBMS_METADATA.GET_DDL('TABLE','PERSON') from DUAL;
Related
I'm currently trying to create txt files from all tables in the dbo schema
I have like 200s-300s tables there, so it would takes up too much times to create it manually..
I was thinking for creating a loop.
so as example (using AdventureWorks2019) :
select t.name as table_name
from sys.tables t
where schema_name(t.schema_id) = 'Person'
order by table_name;
This would get all the table name within the Person schema.
So I would loop :
Table input : select * from ${table_name}
But then i realized that for txt files, i need to declare all the field and their data types in pentaho, so it would become a problems.
Any ideas how to do this "backup" txt files?
Using Metadata Injection and more queries to the schema catalog tables in SQL Server. You not only need to retrieve the table name, you would need to afterwards retrieve the columns in that table and the data types, and inject that information (metadata) to the text output step.
You have in the samples directory of your spoon installation an example on how to use Metadata Injection, use it, along with the documentation, to build a simple example (the check to generate a transformation with the metadata you have injected is of great use to debug)
I have something similar to copy data from one database to another, both in Oracle, but with SQL Server you have similar catalog tables as in Oracle to retrieve the information you need. I created a simple, almost empty transformation to read one table and write to another. This transformation has almost no information, only the database origin in the Table Input step and the target database in the Table Output step:
And then I have a second transformation where I fill up all the information (metadata) to inject: The query to perform in the Table Input step, and all the data I need in the Table Output: Target table, if I need to truncate before inserting, the columns from (stream field) and to (Table field):
I would like to be able to refer to tables with a certain naming schema to make my code uniform, but I am pulling tables from different environments with different naming schema. If I want all my tables to have names like example_table_1 and example_table_2, but the second one is something like TB_ex_2, is there a way to give that table an attribute so that I can also call select * from database.example_table_2, and it will know to refer to TB_ex_2?
I understand that I can alias tables, e.g. select * from TB_ex_2 example_table_2, but I am trying to avoid that. Renaming each table is also not an option, because those names need to be retained to identify which environment they are coming from.
Hive does not support synonyms. The workaround is to create a view:
CREATE VIEW table2
AS SELECT * from table1;
Also you can create many tables on top of the same location(data).
An external system granted to my system a view named V_EXT so that I can make selections on it, reading all its content:
SELECT *
FROM V_EXT;
this view has a lot of fields and I would like to create an empty table in my system with the exactly same attributes of this view (same names and same types). Is there a way to do this without simply guessing from the content I received what each attribute is?
I am using Oracle SQL Developer.
With Code.
create table objects_copy2
as
select *
from all_objects
where 1=2; -- add this line if you want NO data, otherwise you get all the data too
With SQL Developer specifically, it's actually harder. You would need to find the underlying OBJECT(s) used in the query. Then look up those data types, and manually build out your CREATE TABLE statement.
CREATE TABLE AS SELECT is the way to go. (Docs)
Note there are some limitations, for example this won't pick up Identity Column definitions from the source table used in the view.
An example:
I have a database schema which is identical in files 1.sqlitedb through n.sqlitedb. I use a view to 'merge' all of the databases. My question is: when i insert into the view, into which database does the data get inserted into? Is there any way to control which gets the data? The way that i need to split the data depends on the data itself. Essentially, i use the first letter of a field to determine the file that it gets inserted into. Any help would be appreciated. Thanks!
Writing to views is NOT supported for SQLite like it is with other dbs.
http://www.sqlite.org/omitted.html
In order to achieve similar functionality, one must create triggers to do the necessary work.
We need to implement instead of trigger on the view (VIEW_NAME) . So when insert/update happens view . we can insert update underlying object (TABLE_NAME) in the trigger body.
CREATE TRIGGER trigger_name instead of INSERT on VIEW_NAME
BEGIN
insert into TABLE_NAME ( col1 ,col2 ) values ( :new.col1, :new.col2);
END;
I'm not sure I understand your question, but have you looked into using the ATTACH DATABASE command? It allows you connect separate database files to a single database. You can control INSERTs into a specific database by prefixing the database name (INSERT INTO db1.Table).
http://www.sqlite.org/lang_attach.html
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.