Lets say I create a table in snowflake called Employee with EmployeeID and EmployeeName. I would check in the Create table script for this table to my github repo and get this deployed using sqitch. If in the next release, there is a need to add a new column to this table, can I accomplish this by just adding a new column to the existing Create table scripts. Does sqitch have the ability to compare github and my target DB to understand and generate ALTER scripts in this case?
Never mind, I did some more research and figured that Sqitch follows the imperative approach. Which means that it needs us to write the Alter statements in this case.
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');
Let's say I created a table test_table in development just to test a trigger, this trigger would then be reused in many other tables (future and existing).
So I code the trigger, test it, all good! But at the moment, if I want to replicate it, I will have to copy it from test_table's triggers and edit it.
So if someone deletes the table accidentally, the trigger is gone, and I don't have it saved nowhere else. Or if I just want to delete random test tables in our database, I can't.
What's a recommended way to save a trigger as a "template" in oracle? So I can reuse it in other tables and have it not be dependant of a random test table, or any table.
There are a lot of ways you can keep a copy of your TRIGGER SQLText.
Here's a few examples.
In Version Control:
You can use any of the many version control tools to maintain a versioned history for any code you like, including SQL, PL/SQL, etc. You can rewind time, view differences over time, track changes to the template, even allow concurrent development.
As a Function:
If you want the template to live in the database, you can create a FUNCTION (or PACKAGE)that takes as parameters the target USER and TABLE, and it replaces the USER and TABLE values in its template to generate the SQLTEXT required to create or replace the template TRIGGER on the target TABLE. You can make it EDITIONABLE as needed.
In a Table:
You can always just create a TABLE that holds template TRIGGER SQLText as a CLOB or VARCHAR2. It would need to be somewhere where it isn't likele to be "randomly" deleted, though. You can AUDIT changes to the TABLE's data, to see the template change over time. Oracle has tons of auditing options.
In the logs:
You can just log (all) DDL out. If you ENABLE_DDL_LOGGING, the log xml will have a copy of every DDL statement, categorized, along with when and where it came from.
I need sone help in PL/SQl.
So my problem is, the following problem:
There is a table called: temp_table and I need to create a temp_table without drop/truncate option. It needs because all the time a table's data changing.
So I know its weird, but this is necessary for my daily job.
The script work like this:
The script does a text import to table, and the table is given. It use a dblink to connect the database. It works, but all the time I have to use DROP. But I need ( if its possible) to create an existing table without drop/truncate.
Can someone help me?
Thanks a lot.
Sorry for no sql code, but i think it doesn't necessary.
I think the concept you want is the external table. With external tables the data resides in OS files, such as CSVs. This allows us to swap data sets without dropping the table.
Find out more.
I take it you want to drop the table because you want to reload it, but you also want there to be as close to constant up-time as possible?
I would create two temp tables. You already have one called:
temp_table
Create another called:
temp_table_new
Load your new data into temp_table_new, then run a rename on it like so:
RENAME TABLE temp_table TO temp_table_old
temp_table_new TO temp_table
Then
drop table temp_table_old
This will be super fast, have very little downtime, and allow you to have the functionality you've described.
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've database with 15 tables. Now due to development process one column has to added to all the tables in the database. This changes should not affect the existing process because some other services are also consuming this database. So to accomplish it I thought of creating a new database. Is there are any other way to do it.
Usually it should be enough to create a new schema ("user") and create the tables in that new schema. In Oracle, identically named tables can exist in several schemas.
CREATE USER xxx IDENTIFIED BY yyy
you can create another schema for development and import the table to new schema.Developer should use the development schema instead of production schema.you can also create new database and import from current database but it might be last option
What's wrong with alter table T add (COL varchar2(5)); ?
Of course dependend stored procedures or packages become invalid.
You can leave them alone, then the first call would return an exception and auto-recompile the called procedure. Or you can alter procedure P compile;.