I am in need of guidance on creating database link for 1 to many relationship.
I have a class called Orders. The class unique/primary key is id.
I have a second class called Order_Details. Order_Details contains order_id (relationship back orders.id)
Every type of create link command I have executed, returns an error specifying that link cannot be created because of multiple records.
Please see below for my sample data and desired results below.
My goal is to have a link called Detail, on Orders that contains all Order_Details for the order.id record
Current Data
Desired Results
Actually,
I was able to figure it out on my own.
A combination of LINKLIST and INVERSE did the trick.
Originally, I was executing LINKSET without INVERSE
syntax used:
CREATE LINK Detail TYPE LINKLIST FROM Order_Details.order_id TO Orders.id INVERSE;
Thanks for taking the time to read my question.
Related
In my model I want to loop through the database which contains multiple columns (see example) by an event. The idea behind it is that I want to create dynamic events based on the rows in the database.
But I've no clue how to iterate through a database in anylogic and also was not able to find an example of a loop with a database.
The dummycode of my problem would look something like this:
For order in orderdatabase:
Create order based on (order.name, order.quantity, order.arrivaltime, order.deliverylocation)
Where order in the loop is every row of the database, and the value on which the creation is based based on the different column values of that specific row.
Can somebody give me a simple example of how to create such a loop for this specific problem.
Thanks in advance.
Use the database query wizard:
put your cursor into a code field
this will allow you to open the database wizard
select what you need (in your case, you want the "iterate over returned rows and do something" option
Click ok
adjust the dummy code to make it do what you want
For details and examples, check the example models and the AnyLogic help, explaining all options in detail.
I have a PostgreSQL table in an application that holds both parent and child records. There is a column in the table to reference the the parent id where applicable for each child record. The problem is I am trying to import data from an external source where the child record is made up of a sub number of the parent. eg parent_reference_id = 123456000000 and a child_reference record for this could 123456000001, 123456000002 and so on. The application itself generates a unique id for each record when I import the data and so its possible to import the child and parent records simultaneously, however the difficulty I'm facing is linking the application generated id for the parent record to the parent_reference_id for the corresponding child records. The only hook I have is that the 1st six digits of the child_value_reference match the 1st six digits of the parent_value_reference and I've tried something like foo = bar(left(value,6)||'000000'; to create a match. However, I don't know how to use this to return the unique_id in a meaningful way and update the matching records. I've tried temporary tables and cte, however my knowledge of postgres is limited and I can't seem to find a solution that fits my problem. Another thing to mention is that these groups can change with updates within the external data so i'd also need a solution to make those updates too. Thanks in advance, Crispian
I have two tables in one MySQLI database. One is called 'actions' and one is called 'links'. But recently I have noticed that many links which I have transfered from my old system don't have any actions attached to it, and I want to count how many they are. So I want to count the amount of links whose id hasn't any entries in the actions table. How can I formulate the statement. There is one id in the links table and one link_id in the actions table.
You are looking for a outer join. without a lot of details, it would look something like:
SELECT * FROM links
LEFT JOIN actions on links.field = actions.field
WHERE actions.ID is NULL;
This will give you all the links records that don't have a corresponding record in actions.
There are two tables, one for Student and one for Borrowed Books. In the Microsoft Access (2010, 2013), it is easy to display a form Student based on the table Student, and other form BorrowedBooks based on the table Borrowed Books with their Record Source pointed.
How to do Form BorrowedBooks showing records for the current student showing on the Form Student one at one time? I'm looking to learn both VBA script and using the built-in controls to achieve the result.
Relationship between has been built. And it's one student to many books relationship.
One VBA approach like:
DoCmd.OpenForm "BorrowedBooks", , , "StudentID = " & Me.StudentID
The real trick is figuring out which event to put code into.
Another option is to use form/subform arrangement - main form bound to Students table and subform bound to BorrowedBooks. Have you looked at Microsoft Lending Library database template?
so if my understanding of your question is clear then you need to join operation on the tables
SELECT *
FROM
student
INNER JOIN borrowedbooks ON (The two table'S related column ie student.pk=borrowedbooks.fk)
you can also add a where clause if you want from here you can state you primary key in student table and it relationshi
Can any one help me why this error occurs when i update using sqlDataadapter with join query
Dynamic SQL generation is not supported against multiple base tables.
You have a "join" in your main query for your dataset (The first one in the TableAdapter with a check by it). You can't automatically generate insert/update/delete logic for a TableAdapter when the main query has multiple tables referenced in the query via a join. The designer isn't smart enough to figure out which table you want to send updates to in that case, that is why you get the error message.
Solution. Ensure that your main query only references the table you want the designer to write insert/update/delete code for. Your secondary queries may reference as many tables as you want.
It was in the case that i was trying to set value for identity column in my datarow. Simply i deleted the code to set value for identity column and it will work.
My Scenario:
Database:
uin [primary, identity]
name
address
Whenever i tried to set the datarow("uin") the error occurs. But works fine with datarow("name") and datarow("address").
Hope it works for you too