I am trying to auto increment data, which is not Id, I have used Sql Identity on Id so can't use it anymore. I tried sql sequence to bind data column and it works if I add information from sql via script but it does not work on adding from visual studio. I tried to [DatabaseGenerated(DatabaseGeneratedOption.Computed)] but it does not work too. I have been searching this topic for 2 days in web but can't find any solution
You can use SQL Sequences for this. According to the documentation by Microsoft
A sequence is a user-defined schema bound object that generates a sequence of numeric values according to the specification with which the sequence was created. The sequence of numeric values is generated in an ascending or descending order at a defined interval and can be configured to restart (cycle) when exhausted. Sequences, unlike identity columns, are not associated with specific tables. Applications refer to a sequence object to retrieve its next value. The relationship between sequences and tables is controlled by the application. User applications can reference a sequence object and coordinate the values across multiple rows and tables.
You can create a sequence using the syntax below:
CREATE SEQUENCE OrderNumber
START WITH 1
INCREMENT BY 1 ;
GO
To check how it can be used in MVC, please check this post.
Hope this helps!
Related
I am trying to create an application for work. The app will be used internally and should allow us to assign some barcode numbers to our product SKUs. I am using Visual Studio / Basic 2010 Express to build this as my very limited and beginners experience is with VS 2010 Express.
I'll give a bit of information about how I see this application working and then I'll get on with my actual question:
I see the app allowing us to create a new Product in the database by a user entering the SKU and description of the product and then the app will assign this product the next available base number for the barcode and from there the app will (if required) generate the correct EAN13 and GTIN14 barcodes and store them against that SKU.
As a company we have a large range of barcode numbers we can use and we have split this large range up so that the first 50,000 (for example) are for our EAN13 codes, the next 50K are for our GTIN14 codes for Inner Cartons and the remaining 50K are for Master Cartons.
So in order to achieve this I have my Product table which contains the fields 'SKU', 'Description' and 'BarcodeBase'. I have managed to set the BarcodeBase field as unique and I am attempting to use AutoIncrement(Seed & Step) to make sure that this assigns the product a base barcode (before I calculate the check digit) that falls within the EAN13 range as described above...
So finally my question is: Is there a way I can put an upper limit on AutoIncrement so that on the off chance, way way in the future, the base barcode number will not overflow into the next range?
I've been googling unsuccessfully for an answer and I am only coming across things which talk about the data type of the field having a limit. For example the upper limit of an Int32 type. Through my searches I have become vaguely aware of the 'Expression' property of the field and also the possibility of coding a partial class - but I don't know if that is the right direction to go in or if there is something much simpler that I am overlooking / have not found.
I would really appreciate any help!
Edit: As per GrandMasterFlush's comment - I have added a local database to my VS project. So I think I am using a SQL Server Compact 3.5 db.
Use a CHECK constraint, e.g.:
ALTER TABLE dbo.Product ADD CONSTRAINT ...
CHECK (BarcodeBase BETWEEN 1 AND 50000);
I suggest you do not make BarcodeBase an IDENTITY column in the Product table (IDENTITY is the feature that you are referring to as "autoincrement"). IDENTITY is really designed for surrogate key use only and isn't ideal for meaningful business data. You can't update an IDENTITY column, it isn't necessarily sequential, may have gaps in the number sequence and you also only get to use one IDENTITY column per table. Instead of using IDENTITY in the Product table you can generate the sequence elsewhere, for example by incrementing a single value stored in a single row table.
Current application use JPA to auto generate table/entity id. Now a requirement wants to get a query to manually insert data in to the database using SQL queries
So the questions are:
Is it worth to create a sequence in this schema just for this little requirement?
If answer to 1 is no, then what could be a plan b?
Yes. A sequence is trivial - why would you not do it?
N/A
Few ways:
Use a UUID. UUIDs are pseudo-random, large alphanumeric strings which are guaranteed to be unique once generated.
Does the data have something unique? Like a timestamp, or IP address, etc? If so, use that
Combination of current timestamp + some less unique value in the data
Combination of current timestamp + some integer i that you keep incrementing
There are others (including generating a checksum, custom random numbers instead of UUIDs, etc) - but those have the possibility of overlaps, so not mentioning them.
Edit: Minor clarifications
Are you just doing a single data load into an empty table, and there are no other users concurrently inserting data? If so, you can just use ROWNUM to generate the IDs starting from 1, e.g.
INSERT INTO mytable
SELECT ROWNUM AS ID
,etc AS etc
FROM ...
I'm using ASP.NET MVC3 and Entity Framework with Database first aproach.
I have a table with id(key), number and description columns. I need to generate a number after item insertion. I created instead of trigger where I generate number that I need (it depends on last number that allready exists in database).
The problem is: When users insert items at same time the number in both cases is the same. So for both inserted items trigger fires and inside the trigger select returns same last number of item that allready exsist.
What is the best practice to solve this kind of issue?
Thanks.
I believe this will help you.
http://www.sqlteam.com/article/custom-auto-generated-sequences-with-sql-server
Also, if you're using SQL Server 2012, there is a new feature called SQL Sequence. It's something that Oracle databases have for a long time.
If you need those numbers without any gap, I'd suggest you to lock the table (prevent write), query it, update the row with max(number) and unlock it.
I have a little problem with Enterprise Architect by Sparx System.
Im trying to model database schema for Oracle. I created table with primary key with data type long. But when im trying to modify column properties (set AutoNum = true) I see empty properties. I read documentation of EA and saw that I need to setup this property to generate sequence syntax.
When I change data type to number, or switch database to mysql (for example) everything is alright, there are properties so Im able to modify AutoNum value.
Did you had similar problem and found solution ? or maybe im doing something wrong.
regards
It's becouse Oracle use sequence instead of autoincrement option. I've checked it and I think you have to use NUMBER column type and then set AutoNum property (you have to select Generate Sequences in options to get proper DDL code too). Instead of LONG data type you can set PRECISION and SCALE options on NUMBER type ie NUMBER(8) mean you can have 8 digits number and it can be set up to 38, so if you don't want to store info about every star in the universe will be enought for your scenario :)
Background
I'm writing an adapter for ESE to .NET and LINQ in a Google Code project called eselinq. One important function I can't seem to figure out is how to get a list of indexes defined for a table. I need to be able to list available indexes so the LINQ part can automatically determine when indexes can be used. This will allow much more efficient plans for user queries if appropriate indexes can be found.
There are two related functions for querying index information:
JetGetTableIndexInfo - get index information by tableID
JetGetIndexInfo - get index information by tableName
These only differ in how the related table is specified (name or tableid). It sounds like these would support the function I want but all the info levels seem to require that I already have a certain index to query information for. The only exception is JET_IdxInfoCount, but that only counts how many indexes are present.
JET_IdxInfo with its JET_INDEXLIST sounds plausible but it only lists the columns on a specific index.
Alternatives
I am aware that I could get the index information another way, like annotations on .NET types corresponding to database tables, or by requiring a index mapping be provided ahead of time. I think there's enough introspection implemented to make everything else work out of the box without the user supplying extra information, except for this one function.
Another option may be to examine the system tables to find related index objects, but this is would mean depending on an undocumented interface.
To satisfy this question, I want a supported method of enumerating the indexes (just the name would be sufficient) on a table.
You are correct about JetGetTableIndexInfo and JetGetIndexInfo and JET_IdxInfo. The twist is that the data is returned in a somewhat complex: a temporary table is returned containing a row for the index and then a row for each column in the table. To just get the index names you will need to skip the column rows (the column count is given by the value of the columnidcColumn column in the first row).
For a .NET example of how to decipher this, look at the ManagedEsent project. In the MetaDataHelpers.cs file there is a method called GetIndexInfoFromIndexlist that extracts all the data from the temporary table.