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).
Related
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 certain requirement where in I have been given a table name say ABC, i want to find out which all procedures,packages,mv's,functions refer to that particular table 'ABC' or do a insert or update on that table. Is there any way or query to find this.
Since I cannot look up the code of every object in the schema, I am searching for another way.
You may use Oracle System view dba_dependencies (check with your dba if you don't have access to this view).
select *
from dba_dependencies
where referenced_name='ABC'
and referenced_type='TABLE';
Beware, your objects may also use synonyms. So a second list could come with:
select *
from dba_dependencies
where referenced_name='ABC'
and referenced_type='SYNONYM';
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;
I'm looking for a query allowing me to query all the tables, views, JOBS, and PROCEDURES in the oracle database. I've found some links to queries that will work for the tables and views but I need jobs and procedures. If one query can't be used for all this, I need at least job and procedures.
Here is what I found for the tables and views:
Select TABLE_NAME, COLUMN_NAME from user_tab_columns
TIA
My guess is that you want something like
SELECT name, type, line, text
FROM user_source
WHERE lower(text) like lower('%<<column name>>%');
That will show you any line of code in any pL/SQL object (package, package body, procedure, function, trigger, type, etc.) that contains the column name. If there are multiple tables with identically named columns (i.e. a column name is found in many different tables), all instances will be identified. There isn't a really great way, short of inspecting the code, to figure out which queries refer the name column in one particular table. You could potentially look to see whether the NAME and TYPE from USER_SOURCE appear in DBA_DEPENDENCIES as referencing the particular table you're interested in. But that just shows you table-level dependencies at an object level and your object may depend on a large number of different tables.
I was given an oracle dump file for an existing system. The dump file contained the table PARTS but when I look on the queries being done by the code. It uses mostly M_PARTS and just on one occasion, it uses PARTS. Does oracle allow multiple name on a table?
Note that I am not talking about the alias feature. ie.
Select M_PARTS.*
from PARTS M_PARTS
I want to know if there is a setting to make permanent alias in oracle. Where I just create a table PARTS and I can refer to it as either PARTS or M_PARTS in my query.
Kind of, as you can create synonyms:
CREATE SYNONYM PARTS FOR THE_SCHEMA.M_PARTS;
It is weird however, that the dump file would be inconsistent that way. Are you sure it is the same table? How was the file created?
Yes using synonyms.
Although a synonym was a solution, I found the actual script to build the database and it uses a materialized view instead of a synonym.
create materialized view M_Parts
tablespace USERS
refresh fast
as select * from Parts