I have confusion on how to prevent duplicate InvoiceNo against CompanyId. I just have prepare an Invoice project that has field like CompanyId and InvNo. Both do not have Unique Keys because Company ID and InvoiceNo both have to repeated. as per below
CompanyID InvNo
1 1
2 1
1 2
3 1
4 1
1 3
Now I want to fire a raiserror on duplicate InvoiceNo against a particular CompanyId. How do I implement this. Important: if i create a unique index then duplicate records will not be allowed and it is important to allow except against particular CompanyId
What you are looking for is a Unique Constraint composed of both CompanyId and InvNo. This will let you create only one InvoiceNo = 1 for CompanyId = 1 and will automatically RaisError if you try to insert a duplicate. It will also let you insert InvoiceNo = 1 for CompanyId = 2 thereby (hopefully) satisfying your requiements
This is how I would do it in SQL Server
ALTER TABLE YourTableName
ADD UNIQUE CONSTRAINT InvoiceIdMustBeUniqePerCompany (CompanyId, InvNo)
Your question is not all that straight forward, but assuming you're asking what I think you're asking, it goes something like this...
You need a cable called NextInvoiceNumber, comprising of CompanyID and NextInvoiceNo. Creating a new Company should create a new NextInvoiceNumber - so perhaps use an insert trigger on your Companies table for that...
Write a function to get the next Invoice id for a specific company, and then incremenent the value in the NextInvoiceNumber table (all inside a common transaction).
So, in pseudo code, something like
function GetNextInvoiceNo(CompanyIDCode){
begin transaction;
result = Select NextInvoiceNo from NextInvoiceNumber where CompanyID = CompanyIDCode;
update NextInvoiceNo set NextInvoiceNo = NextInvoiceNo + 1 where CompanyID = CompanyIDCode;
commit transaction;
return result;
}
This function ideally belongs on your database server as a UDF.
From the sample data it appears that the combination of CompanyID + InvNo is unique. If that's true you can create a key on those two fields and upon an attempt to insert a duplicate InvNo that has already been used for a particular CompanyID an error would be thrown.
create table Invoice
(
CompanyID int,
InvNo int,
Primary Key(CompanyID, InvNo)
)
Related
I have two tables a stage table and a target table. I want my target table to hold valid CustomerScore values. Currently, we insert into staging and load to our target table. We do not want to load invalid values(-8.0000). However, if there is a customerNumber with a valid value in our target table we would like to decommission numbers by giving it a customerScore of (-8.0000). This should be the only time this value makes it into the target table, so a record for that CustomerNumber has to already be in the target for this to update that record currently in the target table. My create statement is below
CREATE TABLE stg.CustomerAppreciation (
CustomerId INT identity(1, 1)
,CustomerNumber VARCHAR(50)
,CustomerScore DECIMAL(5, 4)
);
CREATE TABLE ods.CustomerAppreciation (
CustomerId INT identity(1, 1)
,CustomerNumber VARCHAR(50)
,CustomerScore DECIMAL(5, 4)
);
Currently, my target table has two records, each value below belongs to my create table fields.
1 123 0.8468
2 143 1.0342
Now say we want to decommission CustomerID = 2 because there is a record been inserted into staging as
3 143 -8.0000
The target table should now be updated on this CustomerNumber. Making my target table look like:
1 123 0.8468
2 143 -8.0000
This should be the only time we allow -8.0000 into the table when a CustomerNumber already exists. If a customerNumber does not exists in the target table and for some reason -8.0000 is seen in staging it should not be allowed in. How would I write an update query that updates a record in my target table only if that scenario exists and prevents -8.0000 from coming in if it does not exist?
Assuming the staging table only contains one row per customer number (if not, group it to show the highest customer Id), you can use a merge to perform this function. Without checking exact syntax, something like this:
MERGE ods.CustomerAppreciation AS Target
USING (SELECT * FROM stg.CustomerAppreciation WHERE CustomerScore >= 0) AS Source ON Target.CustomerNumber = Source.CustomerNumber
WHEN MATCHED
-- choose your match criteria here
--AND Source.CustomerId > Target.CustomerId
AND NOT EXISTS (SELECT Target.* INTERSECT SELECT Source.*)
THEN UPDATE
SET Target.CustomerScore = Source.CustomerScore;
Not sure if I fully understand the specifics but here is some syntax that should help to at least get you started ...
BEGIN;
MERGE ods.CustomerAppreciation AS X
USING (SELECT CustomerNumber,CustomerScore FROM stg.CustomerAppreciation) AS Y (CustomerNumber,CustomerScore)
ON (X.CustomerNumber = Y.CustomerNumber)
WHEN MATCHED /*AND Y.CustomerNumber = '-8.0000'*/ THEN
UPDATE SET CustomerScore = Y.CustomerScore
WHEN NOT MATCHED BY X /*AND Y.CustomerNumber = '-8.0000'*/ THEN
INSERT (CustomerNumber,CustomerScore)
VALUES (Y.CustomerNumber,Y.CustomerScore)
OUTPUT $action, inserted.* INTO #MyTempTable;
END;
I didn't find a working solution for creating a "lookup column" in a Firebird database.
Here is an example:
Table1: Orders
[OrderID] [CustomerID] [CustomerName]
Table2: Customers
[ID] [Name]
When I run SELECT * FROM ORDERS I want to get OrderID, CustomerID and CustomerName....but CustomerName should automatically be computed by looking for the "CustomerID" in the "ID" column of "Customer" Table, returning the content of the "Name" column.
Firebird has calculated fields (generated always as/computed by), and these allow selecting from other tables (contrary to an earlier version of this answer, which stated that Firebird doesn't support this).
However, I suggest you use a view instead, as I think it performs better (haven't verified this, so I suggest you test this if performance is important).
Use a view
The common way would be to define a base table and an accompanying view that gathers the necessary data at query time. Instead of using the base table, people would query from the view.
create view order_with_customer
as
select orders.id, orders.customer_id, customer.name
from orders
inner join customer on customer.id = orders.customer_id;
Or you could just skip the view and use above join in your own queries.
Alternative: calculated fields
I label this as an alternative and not the main solution, as I think using a view would be the preferable solution.
To use calculated fields, you can use the following syntax (note the double parentheses around the query):
create table orders (
id integer generated by default as identity primary key,
customer_id integer not null references customer(id),
customer_name generated always as ((select name from customer where id = customer_id))
)
Updates to the customer table will be automatically reflected in the orders table.
As far as I'm aware, the performance of this option is less than when using a join (as used in the view example), but you might want to test that for yourself.
FB3+ with function
With Firebird 3, you can also create calculated fields using a trigger, this makes the expression itself shorter.
To do this, create a function that selects from the customer table:
create function lookup_customer_name(customer_id integer)
returns varchar(50)
as
begin
return (select name from customer where id = :customer_id);
end
And then create the table as:
create table orders (
id integer generated by default as identity primary key,
customer_id integer not null references customer(id),
customer_name generated always as (lookup_customer_name(customer_id))
);
Updates to the customer table will be automatically reflected in the orders table. This solution can be relatively slow when selecting a lot of records, as the function will be executed for each row individually, which is a lot less efficient than performing a join.
Alternative: use a trigger
However if you want to update the table at insert (or update) time with information from another table, you could use a trigger.
I'll be using Firebird 3 for my answer, but it should translate - with some minor differences - to earlier versions as well.
So assuming a table customer:
create table customer (
id integer generated by default as identity primary key,
name varchar(50) not null
);
with sample data:
insert into customer(name) values ('name1');
insert into customer(name) values ('name2');
And a table orders:
create table orders (
id integer generated by default as identity primary key,
customer_id integer not null references customer(id),
customer_name varchar(50) not null
)
You then define a trigger:
create trigger orders_bi_bu
active before insert or update
on orders
as
begin
new.customer_name = (select name from customer where id = new.customer_id);
end
Now when we use:
insert into orders(customer_id) values (1);
the result is:
id customer_id customer_name
1 1 name1
Update:
update orders set customer_id = 2 where id = 1;
Result:
id customer_id customer_name
1 2 name2
The downside of a trigger is that updating the name in the customer table will not automatically be reflected in the orders table. You would need to keep track of these dependencies yourself, and create an after update trigger on customer that updates the dependent records, which can lead to update/lock conflicts.
No need here a complex lookup field.
No need to add a persistant Field [CustomerName] on Table1.
As Gordon said, a simple Join is enough :
Select T1.OrderID, T2.ID, T2.Name
From Customers T2
Join Orders T1 On T1.IDOrder = T2.ID
That said, if you want to use lookup Fields (as we do it on a Dataset) with SQL you can use some thing like :
Select T1.OrderID, T2.ID,
( Select T3.YourLookupField From T3 where (T3.ID = T2.ID) )
From Customers T2 Join Orders T1 On T1.IDOrder = T2.ID
Regards.
Database: Oracle
I want to insert data from table 1 to table 2 but the catch is, primary key of table 2 is the combination of first 4 letters and last 4 numbers of the primary key of table 1.
For example:
Table 1 - primary key : abcd12349887/abcd22339887/abcder019987
In this case even if the primary key of table 1 is different, but when I extract the 1st 4 and last 4 chars, the output will be same abcd9887
So, when I use select to insert data, I get error of duplicate PK in table 2.
What I want is if the data of the PK is already present then don't add that record.
Here's my complete stored procedure:
INSERT INTO CPIPRODUCTFAMILIE
(productfamilieid, rapport, mesh, mesh_uitbreiding, productlabelid)
(SELECT DISTINCT (CONCAT(SUBSTR(p.productnummer,1,4),SUBSTR(p.productnummer,8,4)))
productnummer,
ps.rapport, ps.mesh, ps.mesh_uitbreiding, ps.productlabelid
FROM productspecificatie ps, productgroep pg,
product p left join cpiproductfamilie cpf
on (CONCAT(SUBSTR(p.productnummer,1,4),SUBSTR(p.productnummer,8,4))) = cpf.productfamilieid
WHERE p.productnummer = ps.productnummer
AND p.productgroepid = pg.productgroepid
AND cpf.productfamilieid IS NULL
AND pg.productietype = 'P'
**AND p.ROWID IN (SELECT MAX(ROWID) FROM product
GROUP BY (CONCAT(SUBSTR(productnummer,1,4),SUBSTR(productnummer,8,4))))**
AND (CONCAT(SUBSTR(p.productnummer,1,2),SUBSTR(p.productnummer,8,4))) not in
(select productfamilieid from cpiproductfamilie));
The highlighted section seems to be wrong, and because of this the data is not picking up.
Please help
Try using this.
p.productnummer IN (SELECT MAX(productnummer) FROM product
GROUP BY (CONCAT(SUBSTR(productnummer,1,4),SUBSTR(productnummer,8,4))))
I am trying to assign ID numbers to records that are being inserted into an SQL Server 2005 database table. Since these records can be deleted, I would like these records to be assigned the first available ID in the table. For example, if I have the table below, I would like the next record to be entered at ID 4 as it is the first available.
| ID | Data |
| 1 | ... |
| 2 | ... |
| 3 | ... |
| 5 | ... |
The way that I would prefer this to be done is to build up a list of available ID's via an SQL query. From there, I can do all the checks within the code of my application.
So, in summary, I would like an SQL query that retrieves all available ID's between 1 and 99999 from a specific table column.
First build a table of all N IDs.
declare #allPossibleIds table (id integer)
declare #currentId integer
select #currentId = 1
while #currentId < 1000000
begin
insert into #allPossibleIds
select #currentId
select #currentId = #currentId+1
end
Then, left join that table to your real table. You can select MIN if you want, or you could limit your allPossibleIDs to be less than the max table id
select a.id
from #allPossibleIds a
left outer join YourTable t
on a.id = t.Id
where t.id is null
Don't go for identity,
Let me give you an easy option while i work on a proper one.
Store int from 1-999999 in a table say Insert_sequence.
try to write an Sp for insertion,
You can easly identify the min value that is present in your Insert_sequence and not in
your main table, store this value in a variable and insert the row with ID from variable..
Regards
Ashutosh Arya
You could also loop through the keys. And when you hit an empty one Select it and exit Loop.
DECLARE #intStart INT, #loop bit
SET #intStart = 1
SET #loop = 1
WHILE (#loop = 1)
BEGIN
IF NOT EXISTS(SELECT [Key] FROM [Table] Where [Key] = #intStart)
BEGIN
SELECT #intStart as 'FreeKey'
SET #loop = 0
END
SET #intStart = #intStart + 1
END
GO
From there you can use the key as you please. Setting a #intStop to limit the loop field would be no problem.
Why do you need a table from 1..999999 all information you need is in your source table. Here is a query which give you minimal ID to insert in gaps.
It works for all combinations:
(2,3,4,5) - > 1
(1,2,3,5) - > 4
(1,2,3,4) - > 5
SQLFiddle demo
select min(t1.id)+1 from
(
select id from t
union
select 0
)
t1
left join t as t2 on t1.id=t2.id-1
where t2.id is null
Many people use an auto-incrementing integer or long value for the Primary Key of their tables, and it is often called ID or MyEntityID or something similar. This column, since it's just an auto-incrementing integer, often has nothing to do with the data being stored itself.
These types of "primary keys" are called surrogate keys. They have no meaning. Many people like these types of IDs to be sequential because it is "aesthetically pleasing", but this is a waste of time and resources. The database could care less about which IDs are being used and which are not.
I would highly suggest you forget trying to do this and just leave the ID column auto-increment. You should also create an index on your table that is made up of those (subset of) columns that can uniquely identify each record in the table (and even consider using this index as your primary key index). In rare cases where you would need to use all columns to accomplish that, that is where an auto-incrementing primary key ID is extremely useful—because it may not be performant to create an index over all columns in the table. Even so, the database engine could care less about this ID (e.g. which ones are in use, are not in use, etc.).
Also consider that an integer-based ID has a maximum total of 4.2 BILLION IDs. It is quite unlikely that you'll exhaust the supply of integer-based IDs in any short amount of time, which further bolsters the argument for why this sort of thing is a waste of time and resources.
I have a table (in SQL Server) like:
UserId CompanyId UserName Position
1 1 John 1
2 2 Adam 1
3 2 Nick 2
4 1 Mark 2
5 3 Jack 1
UserId is the PK with autoincrement. CompanyID is a FK. Position is just a sequential counter for the users (per company).
When a new user record is inserted (via LINQ) for a company, I want the Position to be incremented as well. Currently I get the MAX+1 of the Position for the given CompanyId and then assign it to the new record. The problem is that concurrent insert operations often result in identical Position values.
I tried incrementing the position in an insert trigger for uniqueness, but LINQ doesn't reflect the updated value automatically.
How can I go about fixing this through LINQ-to-SQL or directly as a TSQL query?
Any help is appreciated. Thanks!
I can tell you about TSQL query.
you can use
IDENT_CURRENT - which gives you the last id inserted into the table by anyone.
if that is not what you want than try - SCOPE_IDENTITY
My 2 cents:
begin transaction
declare #v int
select #v = isnull((select max(field2)+1 from t1), 1)
insert into t1 (field2) values (#v)
commit transaction
-- just checking
select * from t1
You can add a unique constraint on CompanyID and Position to prevent duplicates.
create table Users
(
UserId int identity primary key,
CompanyId int not null,
UserName char(10) not null,
Position int not null,
unique(CompanyId, Position)
)
Instead of duplicates you get an exception and in your code you can do something about that like perhaps a retry.