I would like to know, if azure app service provides any transaction, so that i could roll back if any thing fails on insertion or updation.
Below is the scenario in which i need transaction support.
I am using Azure App service in .net. The mobile client is calling the Azure app service. I have a requirement in which one table primary key is referenced as a foreign key to another table..So if the referenced foreign key table fails on insertion, i do have to roll back the insertion from the first table.
Thanks in Advance.
I have a requirement in which one table primary key is referenced as a foreign key to another table..So if the referenced foreign key table fails on insertion, i do have to roll back the insertion from the first table.
AFAIK, the referenced entity would be inserted by default. If you create a new TableA record along with the new referenced TableB record against the Table A endpoint, then there has the transaction. Here is a similar issue, you could refer to it.
When you insert a new record to TableB, then send another request to add new record to TableA with the foreign key (TableB's primary key), at this time, there is no transaction. If the insertion for TableA fails, then you need to send a request to delete the previous inserted TableB record manually.
Moreover, I would recommend you follow adrian hall's book about Relationships.
Related
I have a parent table (Assessment) with two children tables with 1 to 1 relationships defined. To make sure that a child row is never added that does not have a parent entry, I want to add an insert trigger to the child table (ConsequenceAssessment) in this case. The following ConsequenceAssessment BeforeChange trigger fires but I cannot find how to reference the INSERTED rowset. There is an OLD recordset that works for an update; but, how do I access the inserted row. The following is my best attempt - but, the ConsequenceAssessment table does not yet include the new row and therefore, the trigger always hits the RaiseError.
UPDATE: Just found out that I can enforce Referential Integrity on a one-to-one relationship within Access (rookie misunderstanding). I would still like to know how to access the updated recordset. With MS SQL Server, this is implemented via the INSERTED table which is available within the scope of an INSERT trigger. So, what is the equivalent in MS Access.
In a Before Change data macro, [fieldname] refers to the new value and [old].[fieldname] refers to the old value (which would be Null for an insert).
In your particular case [ConsequenceAssessment].[id] appears to be the primary key for that table, not a foreign key referring to the [Assessment] (parent) table. So, the lookup is simply searching for the wrong key value in the parent table.
Hi I have two table Customer and Orders.
Customer Id is primary in Customer and Foreign key in Orders.
I have done the following coding:
ForeignKeyConstraint custOrderFK = new ForeignKeyConstraint("CustOrderFK",
custDS.Tables["CustTable"].Columns["CustomerID"],
custDS.Tables["OrdersTable"].Columns["CustomerID"]);
custOrderFK.DeleteRule = Rule.None;
custDS.Tables["OrdersTable"].Constraints.Add(custOrderFK);
Since I have mentioned custOrderFK.DeleteRule = Rule.None; deleting an entry in customer's table should not affect order's table. But I am not able to delete a row from Customer table. It throws exception. I am new to ado.net.
Maybe something is wrong with my understanding of rules.
Use delete cascade option with foreign key.
I have a "services" table for detailing services that we provide. Among the data that needs recording are several small one-to-many relationships (all with a foreign key constraint to the service_id) such as:
service_owners -- user_ids responsible for delivery of service
service_tags -- e.g. IT, Records Management, Finance
customer_categories -- ENUM value
provider_categories -- ENUM value
software_used -- self-explanatory
The problem I have is that I want to keep a history of updates to a service, for which I'm using an update trigger on the table, that performs an insert into a history table matching the original columns. However, if a normalized approach to the above data is used, with separate tables and foreign keys for each one-to-many relationship, any update on these tables will not be recognised in the history of the service.
Does anyone have any suggestions? It seems like I need to store child keys in the service table to maintain the integrity of the service history. Is a delimited text field a valid approach here or, as I am using postgreSQL, perhaps arrays are also a valid option? These feel somewhat dirty though!
Thanks.
If your table is:
create table T (
ix int identity primary key,
val nvarchar(50)
)
And your history table is:
create table THistory (
ix int identity primary key,
val nvarchar(50),
updateType char(1), -- C=Create, U=Update or D=Delete
updateTime datetime,
updateUsername sysname
)
Then you just need to put an update trigger on all tables of interest. You can then find out what the state of any/all of the tables were at any point in history, to determine what the relationships were at that time.
I'd avoid using arrays in any database whenever possible.
I don't like updates for the exact reason you are saying here...you lose information as it's over written. My answer is quite simple...don't update. Not sure if you're at a point where this can be implemented...but if you can I'd recommend using the main table itself to store historical (no need for a second set of history tables).
Add a column to your main header table called 'active'. This can be a character or a bit (0 is off and 1 is on). Then it's a bit of trigger magic...when an update is preformed, you insert a row into the table identical to the record being over-written with a status of '0' (or inactive) and then update the existing row (this process keeps the ID column on the active record the same, the newly inserted record is the inactive one with a new ID).
This way no data is ever lost (admittedly you are storing quite a few rows...) and the history can easily be viewed with a select where active = 0.
The pain here is if you are working on something already implemented...every existing query that hits this table will need to be updated to include a check for the active column. Makes this solution very easy to implement if you are designing a new system, but a pain if it's a long standing application. Unfortunately existing reports will include both off and on records (without throwing an error) until you can modify the where clause
I'm looking for the best way to handle deleting linked data across three PostgreSQL tables (technically more, but it's the same idea).
The three tables are agency, address, and agency_address. An agency can have multiple addresses so the agency_address is just a link table with two columns, agency_id and address_id (defined as their respective foreign keys)
I want to set it up so that when an agency is deleted it will remove the link table row in agency_address and the related address row automagically. (So if an agency is deleted, so are all its addresses)
I can get it to clear the link table, but not sure how to get to the address table.
(Also address is a generic model and will be referenced by others, like a 'site' which will have their own link tables.)
Use foreign keys with ON DELETE CASCADE in the table definition.
ALTER TABLE agency_address
ADD CONSTRAINT agency_address_agency_fkey FOREIGN KEY (agency_id)
REFERENCES agency (agency_id) ON DELETE CASCADE;
It seems uncertain that you should delete addresses automatically, too.
If so, your data model is wrong and addresses should depend on agencies directly, with a foreign key constraint similar to the one above, no n:m linking table necessary.
Edit after more info:
So addresses can be linked to agencies or sites, but never to both at the same time.
The model could work as you have it, but you would have to make sure somehow that an address linked to an agency isn't linked to a site, too.
The foreign key constraint between address and agency_address points in the "wrong" direction, so you cannot simply add another ON DELETE CASCADE. You could implement it with an additional foreign key, but that's tricky. This approach per trigger is much simpler:
CREATE OR REPLACE FUNCTION trg_agency_address_delaft()
RETURNS trigger AS
$BODY$
BEGIN
DELETE FROM address
WHERE address_id = OLD.address_id;
END;
$BODY$
LANGUAGE plpgsql;
CREATE TRIGGER delaft
AFTER DELETE ON agency_address
FOR EACH ROW EXECUTE PROCEDURE trg_agency_address_delaft();
More about trigger functions and triggers in the manual.
I have 2 tables in sql server with primary keys set to identity. They are related and work fine.
I then created a form in vb 2008 and tried inserting some values into my database the respective primary keys work but the primary key in the parent table wont show up in the child table.I did create a relationship in vb using ado.net and all the details of my table are defineed in the data table. For example
cust tables (custid,name,..)
book table(bookid,bookname,..,custid)
in vb my insert statement is something like Insert into cust(name) values(#name)
insert into book(bookname) values(#bookname). I do not include the id columns as they auto generate in the database(tables).
My question is that how do i get to insert the custid in the book table when the data is stored back into the tavles in my database.
Please advice with an example as im not half as good as you guys.
Kind Regards
You have to know which customer you want to associate with the book before INSERTing the book. If you don't know before hand, you can't. So somewhere in your Form there should be a way to select a customer. Then when you create a book, you grab that customer's ID and insert it along with the other book info.
You don't actually say that you created a foreign key constraint between the two tables!
You need to:
Ensure that you create an explicit foreign key on the BOOK table to point to a customer in the CUST table.
First insert the customer.
Then find out what the customer's auto-generated ID was. That value is in ##IDENTITY. Store it somewhere e.g. #CUSTID.
Insert the book, specifying #CUSTID as the customer's ID.