I'm running an application simulates selling air plane tickets.
Using a simple schema (1-n):
SEAT
------
id_seat
description
position
BOOKING
---------
id
customer
id_seat
I'd like to produce a Query using either JPA API or Criteria which provides me a list of all available SEATs. That is, all SEAT Objects which do not exist (not booked) in the BOOKING table. (SEAT.id_seat = BOOKING.id_seat)
Can anybody give me a clue which is the best option to produce such a Query?
select seat from Seat seat
where seat.id not in (
select seat2.id from Booking booking
inner join booking.seat seat2)
Related
I've looked all over the internet and I fail to get this query running as expected.
I've got a table of invoices and some invoices are related to one another because they belong to the same project.
My ticket says I've got to get the PREVIOUS invoice based on a provided invoice.
Say Project A has 10 invoices, and I'm looking at invoice #4, I've got to write a query which will return the ID of the previous Invoice. Bear in mind, the invoice table is home to all sorts of projects, and each project could have many invoices on their own, so I want to avoid getting many IDs back and then iterating over them.
To illustrate the issue, I've written this fiddle.
It works somewhat acceptably when I don't filter for steps.id, but that means returning hundreds of IDs to sift through.
I've tried and tried but I can't seem to get the column previousStep to be kind of bound to the ID column.
Simply find the invoice with the next largest id for the same project:
SELECT inv2.id
FROM invoice AS inv1
JOIN invoice AS inv2
ON inv1.project = inv2.project AND inv1.id > inv2.id
WHERE inv1.id = 1057638
ORDER BY inv2.id DESC
LIMIT 1;
I have two collections
Customers
Products
I have a field called "orders" in each of my customer document and what this "orders" field does is that it stores a reference to the product Id which was ordered by a customer, now my question is since I'm referencing product Id and if I update the "title" of that product then it will also update in the customer's order history since I can't embed each order information since a customer may order thousands of products and it can hit 16mb mark in no time so what's the fix for this. Thanks.
Create an Orders Collection
Store ID of the user who made the order
Store ID of the product bought
I understand you are looking up the value of the product from the customer entity. You will always get the latest price if you are not storing the order/price historical transactions. Because your data model is designed this way to retrieve the latest price information.
My suggestion.
Orders place with product and price always need to be stored in history entity or like order lines and not allow any process to change it so that when you look up products that customers brought you can always get the historical price and price change of the product should not affect the previous order. Two options.
Store the order history in the current collection customers (or top say 50 order lines if you don't need all of history(write additional logic to handle this)
if "option1" is not feasible due to large no. of orders think of creating an order lines transaction table and refer order line for the product brought via DBref or lookup command.
Note: it would have helped if you have given no. of transactions in each collection currently and its expected rate of growth of documents in the collection QoQ.
You have orders and products. Orders are referencing products. Your problem is that the products get updated and now your orders reference the new product. The easiest way to combat this issue is to store full data in each order. Store all the key product-related information.
The advantage is that this kind of solution is extremely easy to visualize and implement. The disadvantage is that you have a lot of repetitive data since most of your products probably don't get updated.
If you store a product update history based on timestamps, then you could solve your problem. Products are identified now by 3 fields. The product ID, active start date and active end date. Or you could configure products in this way: product ID = product ID + "Version X" and store this version against each order.
If you use dates, then you will query for the product and find the product version that was active during the time period that the order occurred. If you use versions against the product, then you will simply query the database for the particular version of the product itself. I haven't used mongoDb so I'm not sure how you would achieve this in mongoDb exactly. Naively however, you can modify the product ID to include the version as well using # as a delimiter possibly.
The advantage of this solution is that you don't store too much of extra data. Considering that products won't be updated too often, I feel like this is the ideal solution to your problem
I am doing a PoC using dotnet and ksql.
https://github.com/pablocastilla/kafkiano/
The overall idea is to see if I can implement business logic using KSQL. In the example I introduce devices in the stock and make orders from it. The example consists in this:
Two main streams:
Inventory stream receives the adding event to inventory.
Orders stream receives orders of products.
With those streams I create two tables:
ProductStock: it just adds the products to the stock
Orders: counts the orders by product
After those two tables I create another table with the difference between the orders and the products in the inventory, just to know if there are products left.
With a join in that last table and the order stream I can have the stock left when that order is processed.
I am introducing the events using the productname as key. So far it works well in my machine, but my questions are:
Is this consistent in a big production environment? I would like to know restrictions about when the consistency is broken when a lot of events are received in parallel.
How can I know which queries are executed before others? I need to count the difference between inventory and orders before the I join that difference with the order stream
Thanks
KSQL:
//INVENTORY STREAMS
CREATE STREAM InventoryEventsStream (ProductName VARCHAR, Quantity INT) WITH (kafka_topic='INVENTORYEVENTS', key='ProductName', value_format='json');
//TABLE GROUPING BY PRODUCT
CREATE TABLE ProductsStock as select ProductName,sum(Quantity) as Stock from InventoryEventsStream group by ProductName;
// ORDERS STREAMS
CREATE STREAM OrdersCreatedStream (ProductName VARCHAR,Quantity INT, OrderId VARCHAR, User VARCHAR) WITH (kafka_topic='ORDERSEVENTS', key='ProductName', value_format='json');
//TABLE GROUPING BY PRODUCT
CREATE TABLE ProductsOrdered as select ProductName as ProductName,sum(Quantity) as Orders from ORDERSCREATEDSTREAM group by ProductName;
// join with the difference
CREATE TABLE StockByProductTable AS SELECT ps.ProductName as ProductName,ps.Stock - op.Orders as Stock FROM PRODUCTSORDERED op JOIN ProductsStock ps ON op.ProductName = ps.ProductName;
//logic: I want the stock left when I make an order
SELECT ocs.OrderId,ocs.User,sbpt.Stock FROM OrdersCreatedStream ocs JOIN StockByProductTable sbpt ON sbpt.ProductName = ocs.ProductName;
I copy and paste the github answer I got from the confluent team:
"I get your question. A minimal answer for your question is, it executes as soon as your message is available in the stream.
A good analogy would be a machinery which is always running.
Whenever a payload enters inside, it will just process it. Now it comes to you on the chaining part. Are you inserting some payload to a new record stream after processing? Then yes, you can call it 'chaining'. Once you run / execute CTAS/ CSAS statements you see something like 'Table/Stream created and Running' , that is exactly what it means.
You have ignited an always running query!"
In TFS 2013 Microsoft "fixed" a bug which allowed to map a WorkItem's state to the "Done" state in the Kanban board.
This feature was heavily used in our company. There is a petition to bring it back back but I don't think it will make it:
http://visualstudio.uservoice.com/forums/121579-visual-studio/suggestions/5589316-allow-multiple-complete-meta-state-mapping-in-tfs
In order to migrate TFS2012 to TFS2013 I would like to know where the customized "Done" state columns in TFS 2012 is stored in the database to create a report which shows which team used which WorkItem state as their "Done" state.
TFS2012 Kanban Board looked like that (note the dropdown):
TFS2013 Kanban Board looks like that (note NO dropdown):
I do have access to the TFS Collection database and I would like to create a SQL query which shows me all the customization of this column in TFS 2012.
How can I get for "My WorkItem" the for every Team Project and every Team the customized "Done" state in TFS2012 database?
What other tables do I need to link to in order to get those states?
So far I could only get the TeamId, Name, ColumnType ProjectId but not the effective WorkItem and the "Done" column customization. How can I do that?
SELECT
tbl_Board.TeamId,
tbl_Board.Revision,
tbl_BoardColumn.Name,
tbl_BoardColumn.ColumnType,
tbl_WorkItemTypeExtensions.Description,
tbl_BoardColumn.[Order],
tbl_WorkItemTypeExtensions.ProjectId
FROM
tbl_WorkItemTypeExtensions
RIGHT OUTER JOIN tbl_Board ON
tbl_WorkItemTypeExtensions.Id = tbl_Board.ExtensionId
LEFT OUTER JOIN tbl_BoardColumn ON
tbl_Board.Id = tbl_BoardColumn.BoardId
Experts do not recommend accessing TFS DB but you can use Tfs_WarehouseDatabase if Reporting is configured and Data from all project collections is collected and stored in tables that are optimized for reporting.
I do not have a knowledge about the db structures of TFS but going through few important online articles I managed understood quiet a few about it and as I understood the information that is required for you is in WorkItemsAretable.
Team Foundation Server Databases
Work item field and database schema reference
Stack overflow Question Access the Kanban Column (a Team-Specific Field) for a Work Item
With those queries below you can get the state of a certain work item on the Kanban board:
USE Tfs_DefaultCollection
SELECT TOP(10)
MarkerField + 1 as FieldId,
*
FROM tbl_WorkItemTypeExtensions with(nolock)
JOIN tbl_projects on tbl_WorkItemTypeExtensions.ProjectId = tbl_projects.project_id
WHERE tbl_projects.project_name LIKE '%ProjectName%
Copy the result from "FieldId" column to below's query at position XXXXXXXX
SELECT TOP 1000
wid.Id,
wia.State,
wid.StringValue as Kanban,
wia.[Work Item Type],
wia.Title,
tn.Name as Iteration
FROM tbl_WorkItemData wid with(nolock)
JOIN WorkItemsAre wia on wia.ID = wid.Id
JOIN TreeNodes tn on wia.IterationID = tn.ID
WHERE FieldId = XXXXXXXX and RevisedDate = '9999-01-01 00:00:00.000'
ORDER BY Id
Create a Detailed Report using Report Designer
Hope the sources that I have provided above will help your problem!
I contacted the Microsoft Support and they provided me the following answer to my question:
SELECT
board.TeamId,
boardColumn.Name,
workItemTypeExtensions.Rules
FROM
tbl_Board board JOIN
tbl_WorkItemTypeExtensions workItemTypeExtensions ON board.ExtensionId = workItemTypeExtensions.Id JOIN
tbl_projects projects ON workItemTypeExtensions.ProjectId = projects.project_id JOIN
tbl_BoardColumn boardColumn ON board.Id = boardColumn.BoardId
WHERE
projects.project_name LIKE '%< ENTER YOUR PROJECT NAME HERE >%' AND
boardColumn.ColumnType = 2
ORDER BY
board.TeamId,
boardColumn.[Order]
When I check XML in the "Rules" column there I can find exactly what I was looking for.
I have a Product table and a ConfigurableProduct table.
If there are several variations of the same product like a shirt in different colors I create a ConfigurableProduct.
When a user is looking at the catalog he should see a list of products unless there is a ConfigurableProduct, then he should see it with a select box for each variations.
How do I structure the tables for Product and ConfigurableProduct and how do I query the db so I can page through the results?
Thanks
I am going to answer this as if you do not have tables created. I am not sure if that is true though.
The following is a simple example, but I assume you have more data.
products
id
name
configurable_products
id
variation
product_id REFERENCES products(id)
You can just make the configurable products a reference to products.
If you want a listing of products with their configurations then you can do:
select p.name, c.variation
from products p left outer join configurable_products c
on (p.id = c.product_id);
Of course you can just search for all the configurable_products based on the product id too when needed.
As for the paging part of your question you will have to clarify what you mean. You can use limit to limit results if you don't want to get everything at once.