I've been asked to clean up someone else's controller code, which generates an invoice, and I've run into something I don't know how to fix. The code in question is as follows (this is using EF 6: Code First):
var invid = db.TransportJobInvoice.Where(c => c.CompanyId == CompanyId)
.Max(i => i.InvoiceId);
var invoiceId = invid == null ? 1 : (int)invid + 1;
The code is supposed to generate an invoiceId based on the company the invoice is being created for. So a small table of this might look as follows:
------------------------------
| Id | CompanyId | InvoiceId |
------------------------------
| 1 | 1 | 1 |
------------------------------
| 2 | 1 | 2 |
------------------------------
| 3 | 1 | 3 |
------------------------------
| 4 | 2 | 1 |
------------------------------
| 5 | 2 | 2 |
------------------------------
As you can see, the invoiceId would be generated based on the current number of invoices for the company in question. However, I think it's reasonable to suggest that two threads could execute the query before this line is evaluated:
var invoiceId = invid == null ? 1 : (int)invid + 1;
which would result in the same invoiceId being generated for two different invoices.
Is there a simple solution to this, possibly leveraging Entity Framework to do this automatically?
I suggest using the identity for the primary key, very important!
I would then add a column for "CustomerInvoiceID" and put a compound unique key on CustomerID and CustomerInvoiceID".
Then, create a stored procedure that will populate the field CustomerInvoiceID after it has been inserted, here is some pseudo code:
CREATE PROCEDURE usp_PopulateCustomerInvoiceID
#PrimaryKey INT, --this is your primary key identity column
#CustomerID INT
AS
BEGIN
SET NOCOUNT ON;
DECLARE #cnt INT;
SELECT #CNT = COUNT(1)
FROM TBL
WHERE CustomerID = #CustomerID
AND PrimaryKeyColumn <= #PrimaryKey
UPDATE tbl
SET CustomerInvoiceID = #cnt + 1
WHERE PrimaryKeyColumn = #PrimaryKey
END
Two possibilities:
Server-side: Don't compute the max(ID)+1 on the client. Instead, as part of the INSERT statement, compute the max(ID)+1, via an INSERT..SELECT statement.
Client-side: Instead of an incrementing int, generate a GUID on the client, and use that as your InvoiceID.
A rather different approach would be to create a separate table with the NextId for each CustomerId. As new customers are added you would add a new row to this table. It has the advantage that the numbers assigned to invoices can remain unique even if you allow deleting invoices.
create procedure GetInvoiceIdForCustomer
#CustomerId as Int,
#InvoiceId as Int Output
as
begin
set nocount on
begin transaction
update CustomerInvoiceNumbers
set #InvoiceId = NextId, NextId += 1
where CustomerId = #CustomerId
if ##RowCount = 0
begin
set #InvoiceId = 1
insert into CustomerInvoiceNumbers ( CustomerId, NextId ) values ( #CustomerId, #InvoiceId + 1 )
end
commit transaction
end
end
If you use an Identity field in SQL Server, this will be handled automatically.
I don't know if you can make the invoice id auto generated unless it's beinng threated as a foreign key (which I think it isn't).
You problem with multiple threads could be solved using a lock statement.
lock (myLock)
{
var invid = db.TransportJobInvoice.Where(c => c.CompanyId == CompanyId)
.Max(i => i.InvoiceId);
var invoiceId = invid == null ? 1 : (int)invid + 1;
}
This will guarantee that only thread is executing these statements.
Be careful though, this could cause performance issues when those statements are executed alot in parallel and the query takes some significant time to execute.
Related
I am loading some data into a repeater which is coming from two tables. The query against the second table is only selecting the MAX record though, and because of this complexity, I'm having to create a child repeater to then go off and find the Max record to display.
Table A: Activity List
ID | Activity
----+-----------------------
1 | Change Oil Filter
2 | Change brake fluid
3 | Change brake rotors
Table B: Mechanics Log
ID | ActivityID | Date | Mechanic | Comment
---+-------------+-------------+-------------------------------------------
1 | 1 | 2019-27-06 | John | Changed the oil filter
2 | 1 | 2019-26-06 | Sally | No oil filters in stock.
3 | 2 | 2019-20-06 | Sally | Brake fluid flushed.
As stated above, I can produce the following table using two repeaters (one inside the other) and it looks like this.
ActivityID | Date | Mechanic | Comment
-------------+-------------+-----------------------------------------
1 | 2019-27-06 | John | Changed the oil filter
2 | 2019-20-06 | Sally | Brake fluid flushed.
3 | | |
My question is: How can I produce the same table but using only one repeater and 1 T-SQL query? Is it possible? The reason being is that this is a very simple list (shortened for this demonstration) of the full list I have to enable for my mechanics work log, and when i start going to 100+ activities that can be done on a vehicle, the page loads quite slow; assuming because it has to fire off the 2nd repeater + code for each record it has bound.
I also apologize I do not yet have a 'starting point' for you to work with, as nothing I have created has come even close to producing the result in one query. I am having trouble working out how I combine the first part of the query with the MAX(Date) of the 2nd table. Hoping for some assistance from the community to help.
You can use the below query to get the desired result -
Sample Data
Declare #ActivityList Table
(ID int, Activity varchar(100))
Insert into #ActivityList
values
(1 , 'Change Oil Filter' ),
(2 , 'Change brake fluid' ),
(3 , 'Change brake rotors' )
Declare #MechanicsLog Table
(ID int, ActivityID int, [Date] Date, Mechanic varchar(20), Comment varchar(50))
Insert into #MechanicsLog
values
(1 , 1 , '2019-06-27' , 'John' , 'Changed the oil filter' ),
(2 , 1 , '2019-06-26' , 'Sally' , 'No oil filters in stock.' ),
(3 , 2 , '2019-06-20' , 'Sally' , 'Brake fluid flushed.' )
Query
;With cte as
(select ActivityID, Max([Date]) [date] from #MechanicsLog ml
Group By ActivityID
)
Select al.ID, al.Activity, cte.[Date], Mechanic, Comment
from cte inner join #MechanicsLog ml
on cte.ActivityID = ml.ActivityID and cte.[date] = ml.[Date]
right join #ActivityList al on al.ID = ml.ActivityID
order by ID
If you add use the ROW_NUMBER function to add a sequence to each activity ID, you can then filter that to only get the most recent for each activity ID.
select ActivityID, Date, Mechanic, Comment
from
(
select *, ROW_NUMBER() OVER (PARTITION BY ActivityID order by Date desc) RowNumber
from MechanicsLog
) q1
where RowNumber = 1
This gives you the "MAX" record for each ActivityID but with the rest of the record, so you can join to the Activity List table if you want.
select
act.ActivityID, Max(log.[Date]) as [Date]
from
ActivityList act
inner join
MachineLog log on log.ActivityID = act.ActivityID
Group by
act.ActivityID
I have database model:
CONSTRAINT [FK_applications_orders] FOREIGN KEY ([order_id]) REFERENCES [dbo].[orders] ([order_id])
And controller action:
using (var tx = Database.Database.BeginTransaction())
{
var order = Database.Set<Order>().Find(someID);
var apps = Database.Set<Applications>().Where(x => x.Order.Id == order.Id).ToList();
Database.Delete(order);
tx.Commit();
}
I open SQL profiler to inspect what this line var apps = Database... generates, and look at this:
exec sp_executesql N'UPDATE [dbo].[Applications]
SET [order_id] = NULL
WHERE (([application_id] = #0) AND ([order_id] = #1))
',N'#0 uniqueidentifier,#1 int',#0=SomeId,#1=SomeOtherId
So why does the Delete call generate an UPDATE query in SQL server?
You have a FK constraint between Orders and Applications.
When you delete from the Orders table, EF will be doing an update on the Applicatoins table to enforce this constraint.
e.g. you have the following tables
Orders
order_id
1
2
Applications
application_id | order_id
100 | 1
101 | 2
When you delete an order (say order_id 1) if EF didn't do an update you would end up with
Orders
order_id
2
Applications
application_id | order_id
100 | 1 <---- What is this now ???
101 | 2
So it is updating that field to set it to null.
Applications
application_id | order_id
100 | null
101 | 2
What I want is: If key exist in Oracle SQL Table → UPDATE, otherwise do a INSERT
After playing all day yesterday, I managed to get the INSERT part (query below), what I now need is the UPDATE part.
This is why I need it: I have a RadGridView (using Telerik and WPF). When a User clicks on Insert button a new Row is added and after the User hits Enter, the value is Inserted into the Database. But the user can also click on a available row in the RadGridView and update the values, so I need to update the values in my Database too (and not do a INSERT). And that is why I want a query that can perform a Udate or Insert.
Any help is appreciated, also if you have a better way of implementing the INSERT part, I would like to know about it :)
I am using Oracle SQL Developer (Windows 10).
ps. I tried some solutions I found on StackOverflow but could not manage to apply the solutions to my problem.
Table1
+-----------------------------------+------------+--------+
| ID | ORIGTERM | CODE |
+-----------------------------------+------------+--------+
| 126478 | Grass | TEST |
| 374628 | Flower | TEST |
| 128754 | Tree | TEST |
+-----------------------------------+------------+--------+
Table2
+-----------------------------------+------------+---------+
| ID |REPLACETERM |SYSCTLANG|
+-----------------------------------+------------+---------+
| 126478 | Gras | 3 |
| 374628 | Blume | 3 |
| 128754 | Baum | 3 |
+-----------------------------------+------------+---------+
I managed to got the INSERT query, it looks like this (example insert the word 'Plant'):
INSERT ALL
INTO Table1(origterm,code) VALUES (s_origterm,s_code)
INTO Table2(replaceterm) VALUES (s_replaceterm)
SELECT s_origterm, s_code, s_replaceterm
FROM (SELECT 'Plant' s_origterm, 'TEST' s_code, 'Pflanze' s_replaceterm FROM dual)
dual;
I must also update the ID of Table2 to be the same as the one from Table1:
UPDATE Table2 SET Table2.ID = (SELECT Table1.ID FROM Table1 WHERE origterm='Plant')
WHERE replaceterm='Pflanze';
Now I have a table that looks like this:
+-----------------------------------+------------+--------------+------+
| ID | ORIGTERM | REPLACETERM | CODE |
+-----------------------------------+------------+--------------+------+
| 126478 | Grass | Gras | TEST |
| 374628 | Flower | Blume | TEST |
| 128754 | Tree | Baum | TEST |
| 100000 | Plant | Pflanze | TEST |
+-----------------------------------+------------+--------------+------+
SELECT g.ID, origterm, replaceterm, code FROM Table1 g, Table2 ct WHERE g.ID = ct.ID;
Merge does not work with INSERT ALL. If you want to use merge, you should make from both table a view with instead of trigger and than use merge against the view. The whole logic will be inside the trigger.
EDIT: Merge does not work with such views
ORA-38106: MERGE bei Join View oder View mit INSTEAD OF-Trigger nicht unterstützt
You can make two merge statements (one for every table) or one for insert and one for update against view:
CREATE SEQUENCE MYDICT_SEQ START WITH 1 MAXVALUE 9999999999999999999999999999 MINVALUE 0;
CREATE VIEW mydict
AS
SELECT a.id, a.origterm, a.code, b.replaceterm, b.sysctlang
FROM table1 a LEFT OUTER JOIN table2 b ON a.id = b.id;
CREATE OR REPLACE TRIGGER mydict_io
INSTEAD OF INSERT OR UPDATE OR DELETE
ON mydict
FOR EACH ROW
DECLARE
cnt1 INTEGER := 0;
cnt2 INTEGER;
nid NUMBER;
BEGIN
IF INSERTING OR UPDATING THEN
IF :new.id IS NULL AND INSERTING THEN
nid := mydict_seq.NEXTVAL;
ELSE
nid := :new.id;
IF UPDATING THEN
nid := :old.id;
END IF;
SELECT COUNT (*)
INTO cnt1
FROM table1
WHERE id = nid;
END IF;
IF cnt1 = 0 THEN
INSERT INTO TABLE1 (ID, ORIGTERM, CODE)
VALUES (nID, :new.ORIGTERM, :new.CODE);
ELSIF cnt1 > 0 THEN
UPDATE TABLE1
SET ORIGTERM = :NEW.ORIGTERM, CODE = :NEW.CODE
WHERE id = nid;
END IF;
SELECT COUNT (*)
INTO cnt2
FROM table2
WHERE id = nid AND SYSCTLANG = :new.SYSCTLANG;
IF cnt2 = 0 THEN
INSERT INTO TABLE2 (ID, REPLACETERM, SYSCTLANG)
VALUES (nID, :new.REPLACETERM, :new.SYSCTLANG);
ELSE
UPDATE TABLE2
SET REPLACETERM = :new.REPLACETERM
WHERE id = nid AND SYSCTLANG = :new.SYSCTLANG;
END IF;
ELSIF DELETING THEN
DELETE FROM table2
WHERE id = :old.id AND SYSCTLANG = :old.SYSCTLANG;
SELECT COUNT (*)
INTO cnt2
FROM table2
WHERE id = nid;
IF cnt2 = 0 THEN
DELETE FROM table1
WHERE id = :old.id;
END IF;
END IF;
END;
DECLARE
nid NUMBER;
BEGIN
INSERT INTO mydict (ORIGTERM, CODE, REPLACETERM, SYSCTLANG)
VALUES ('Plant', 'TEST', 'Pflanze', 3);
nid := mydict_seq.currval;
UPDATE mydict
SET REPLACETERM = 'Fabrik'
WHERE id = nid;
UPDATE mydict
SET REPLACETERM = 'Usine', SYSCTLANG = 4
WHERE id = nid;
END;
The logic in the instead of trigger can be done better, but I leave this to you ;)
maybe it's too obvious but if you own the 'key' value probably this procedure will work:
DECLARE _flag AS INT = 0;
SELECT COUNT() INTO _flag FROM table1 WHERE ID = key;
IF _flag = 0 THEN
INSERT ...
ELSE
UPDATE ....
END IF;
adjust it to your own code needs and/or ORACLE SQL dialect.
A possible solution is to use the MERGE keyword, documented here:
http://docs.oracle.com/cd/B19306_01/server.102/b14200/statements_9016.htm
Merge is basically an 'upsert' command, meaning that it will update row if exists or insert, if it doesn't.
Finding a solution to an issue in my project
I have stages associated with contracts. That is, a contract can be in either Active stage, Process stage or Terminated stage.
I need to get the no the days the contract was in each stage.
For example, if a contract C1 was in Active stage from 20/10/2013 to 22/10/2013, then in the Process stage from 22/10/2013 to 25/10/2013 and finally in Terminated stage from 25/10/2013 to 26/10/2013 and then again in Active from 26/10/2013 to 28/10/2013, then I should get as result
Active = 4days
Process = 3days
Terminated = 1day /likewise something
My table is created with these columns:
EntryId (primary key)
StageId (foreign key to Stage table)
ContractId (foreign key to contract table)
DateofStageChange
How to do this in SQL Server?
As asked pls find the table entries:
EntryID | Stage ID | Contract ID | DateChange
1 | A1 | C1 |20/10/2013
2 | P1 | C1 |22/10/2013
3 | T1 | C1 |25/10/2013
4 | A1 | C1 |26/10/2013
5 | P1 | C1 |28/10/2013
6 | T1 | C1 |Null(currently in this stage)
Need to use group by on Stage ID
it is important to check and make sure how data is populated in your table.Based on just your sample data and also note that if your entryid is not in sequence then you can create one sequence using row_number.
declare #t table(EntryId int identity(1,1), StageId int,ContractId varchar(10),DateofStageChange date)
insert into #t values
(1,'C1','2013-10-20'),(1,'C1','2013-10-22'),(2,'C1','2013-10-22'),(2,'C1','2013-10-25')
,(3,'C1','2013-10-25'),(3,'C1','2013-10-26'),(1,'C1','2013-10-26'),(1,'C1','2013-10-28')
Select StageId,sum([noOfDays]) [totalNofDays] from
(select a.StageId,a.ContractId,a.DateofStageChange [Fromdate],b.DateofStageChange [ToDate]
,datediff(day,a.DateofStageChange,b.DateofStageChange) [noOfDays]
from #t a
inner join #t b on a.StageId=b.StageId and b.EntryId-a.EntryId=1)t4
group by StageId
You can't with your current structure.
You can get the latest one by doing datediff(d, getdate(), DateOfStageChange)
but you don't have any history so you can't get previous status
This can be done in SQL with CTE.
You didnt provide your tablenames, so you'll need to change where I've indicated below, but it would look like this:
;WITH cte
AS (
SELECT
DateofStageChange, StageID, ContractID,
ROW_NUMBER() OVER (ORDER BY ContractID, StageId, DateofStageChange) AS RowNum
FROM
DateOfStageChangeTable //<==== Change this table name
)
SELECT
a.ContractId,
a.StageId,
Coalesce(sum(DATEDIFF(d ,b.DateofStageChange,a.DateofStageChange)), 'CurrentState`) as Days
FROM
cte AS A
LEFT OUTER JOIN
cte AS B
ON A.RowNum = B.RowNum + 1 and a.StageId = b.StageId and a.ContractId = b.ContractId
group by a.StageId, a.ContractId
This really is just a self join that creates a row number on a table, orders the table by StageID and date and then joins to itself. The first date on the first row of the stage id and date, joins to the second date on the second row, then the daterange is calculated in days.
This assumes that you only have 2 dates for each stage, if you have several, you would just need to do a min and max on the cte table.
EDIT:
Based on your sample data, the above query should work well. Let me know if you get any syntax errors and I'll fix them.
I added a coalesce to indicate the state they are currently in.
I have this sequence generation query that gets the current sequence and increment it to next value. But the increment is not updating. The nextval is always returning 1, the default value from the database
Entity | StartVal | Increment | CurVal | NextVal
----------------------------------------------------
INVOICE | 0 | 1 | 0 | 1
The nextval should be 3, 5, 7 and so on
int nextVal = 0;
using (var db = new MedicStoreDataContext())
{
DAL.LINQ.Sequence seq = (from sq in db.Sequences
where sq.Entity == entity
select sq).SingleOrDefault();
if (seq != null)
{
nextVal = seq.NextVal.HasValue ? seq.NextVal.Value : 0;
seq.NextVal = nextVal + 2;
db.SubmitChanges();
}
}
Have I left something undone?
UPDATE:
Answer: I needed to set the Primary Key and update Sequence class field to include the Primary Key
Usually this is because it hasnt found the unique identifier (or Primary Key) for a table.
In your data descriptions are you sure the table correctly picked up the unique item? - when I first tried this although I had a unique key etc, the table description in c# didnt mark it as unique, so the linq quietly didnt updated it as I had expected, no errors no warnings. Once I corrected the data table in c#, it all went well.
Isn't that the correct behaviour? wouldn't you expect nextVal to be 1 if CurVal is 0? I may be missing something here but it seems like your overcomplicating it a bit. Isn't what you want to do basically
using (var db = new MedicStoreDataContext())
{
DAL.LINQ.Sequence seq = (from sq in db.Sequences
where sq.Entity == entity
select sq).SingleOrDefault();
if (seq != null)
{
seq.CurVal += seq.Increment;
db.SubmitChanges();
}
}
I don't see why you need the whole nextVal bit at all. Please feel free to correct me if I'm wrong.