upc internet akadozik Lesson 1: Validating Data and Permissions in .NET

Generation UPC-A Supplement 5 in .NET Lesson 1: Validating Data and Permissions

Lesson 1: Validating Data and Permissions
Creating UPC A In Visual Studio .NET
Using Barcode maker for VS .NET Control to generate, create Universal Product Code version A image in .NET applications.
www.OnBarcode.com
Recognize UPC Symbol In .NET Framework
Using Barcode recognizer for VS .NET Control to read, scan read, scan image in VS .NET applications.
www.OnBarcode.com
A new feature of SQL Server 2005 is that you can create foreign key constraints on computed columns. You can find information about which foreign key constraints exist in your database by querying the sys.foreign_keys and sys.foreign_key_columns catalog views. Foreign keys are usually queried frequently in user queries and in joins, as well as when SQL Server needs to verify referential integrity when deleting or updating primary key rows. This means that foreign keys usually greatly benefit from being indexed. Indexing is covered in greater detail in 7. When a foreign key constraint raises an error because of a delete or an update of the row that it references, the default reaction is to raise an error message and roll back the statement that violated the constraint. If this is not the result you want, you can change the default action for the foreign key to delete the referenced row, update the referenced column, or both. There are four actions to choose from:
Drawing Bar Code In Visual Studio .NET
Using Barcode printer for Visual Studio .NET Control to generate, create barcode image in .NET applications.
www.OnBarcode.com
Recognize Bar Code In .NET Framework
Using Barcode reader for VS .NET Control to read, scan read, scan image in .NET framework applications.
www.OnBarcode.com
NO ACTION (the default; also available in earlier versions of SQL Server) SET NULL SET DEFAULT CASCADE (also available in SQL Server 2000)
Create Universal Product Code Version A In Visual C#.NET
Using Barcode creation for .NET Control to generate, create GTIN - 12 image in VS .NET applications.
www.OnBarcode.com
UCC - 12 Printer In VS .NET
Using Barcode generation for ASP.NET Control to generate, create GTIN - 12 image in ASP.NET applications.
www.OnBarcode.com
An example implementation is shown below:
UPC A Creator In Visual Basic .NET
Using Barcode creation for .NET framework Control to generate, create UCC - 12 image in .NET framework applications.
www.OnBarcode.com
Making QR Code ISO/IEC18004 In Visual Studio .NET
Using Barcode creator for VS .NET Control to generate, create QR image in .NET applications.
www.OnBarcode.com
CREATE TABLE Test.Customers ( CustomerID INT PRIMARY KEY ); CREATE TABLE Test.Orders ( OrderID INT PRIMARY KEY ,CustomerID INT NULL REFERENCES Test.Customers ON DELETE SET NULL ON UPDATE CASCADE );
UPC-A Supplement 5 Generator In Visual Studio .NET
Using Barcode creator for .NET Control to generate, create Universal Product Code version A image in Visual Studio .NET applications.
www.OnBarcode.com
Encoding Barcode In .NET
Using Barcode generation for Visual Studio .NET Control to generate, create bar code image in Visual Studio .NET applications.
www.OnBarcode.com
The default behavior of the foreign key is NO ACTION. If the foreign key finds an error and NO ACTION is specified, SQL Server rolls back the statement that violated the constraint and raises an error message. SET NULL and SET DEFAULT each cause all the referenced values to be set to either NULL (for SET NULL) or DEFAULT (for SET DEFAULT that is, the default defined on the column) instead of raising an error and rolling back the statement. In the relationship between the Orders and Customers tables shown in the code sample, if a customer is deleted, the CustomerID column is set to NULL for all orders belonging to that customer and no error message is sent to the calling application.
Generating ANSI/AIM Code 128 In Visual Studio .NET
Using Barcode encoder for .NET framework Control to generate, create Code 128B image in .NET framework applications.
www.OnBarcode.com
Draw UPC-E Supplement 2 In VS .NET
Using Barcode generation for .NET Control to generate, create UPC-E Supplement 5 image in Visual Studio .NET applications.
www.OnBarcode.com
5
Code 128B Decoder In Visual Basic .NET
Using Barcode reader for VS .NET Control to read, scan read, scan image in Visual Studio .NET applications.
www.OnBarcode.com
Barcode Maker In Java
Using Barcode generator for BIRT Control to generate, create bar code image in Eclipse BIRT applications.
www.OnBarcode.com
Data Integrity and Error Handling in SQL Server 2005
Bar Code Creation In Java
Using Barcode encoder for Android Control to generate, create barcode image in Android applications.
www.OnBarcode.com
Quick Response Code Maker In Java
Using Barcode maker for Android Control to generate, create Quick Response Code image in Android applications.
www.OnBarcode.com
The CASCADE action causes SQL Server to delete referenced rows for a delete statement (ON DELETE) and update the referenced values (ON UPDATE) for an update statement. Using the same code sample, if the CustomerID column is changed for a row in the Customers table, all corresponding rows in the Orders table are updated with the same CustomerID to reflect the change. If ON DELETE CASCADE is specified for the foreign key constraint and a row in the Customers table is deleted, all referencing rows in the Orders table are deleted. This might sound reasonable, but it might not be possible to implement CASCADE for all foreign key constraints because cyclic references are not supported. For example, in the following script, an error will be raised when you try to add the foreign key FKCustomersLastOrder because it will introduce a cyclic reference. If a customer is deleted, all referencing orders must be deleted, and all customers referencing those orders through the LastOrderID column must be deleted.
Code 3/9 Encoder In VB.NET
Using Barcode maker for VS .NET Control to generate, create Code-39 image in .NET applications.
www.OnBarcode.com
Recognizing EAN 13 In C#.NET
Using Barcode recognizer for VS .NET Control to read, scan read, scan image in .NET applications.
www.OnBarcode.com
CREATE TABLE Test.Customers ( CustomerID INT PRIMARY KEY ,LastOrderID INT NULL ); CREATE TABLE Test.Orders ( OrderID INT PRIMARY KEY ,CustomerID INT NOT NULL REFERENCES Test.Customers ON DELETE CASCADE ON UPDATE NO ACTION ); ALTER TABLE Test.Customers ADD CONSTRAINT FKCustomersLastOrder FOREIGN KEY (LastOrderID) REFERENCES Test.Orders (OrderID) ON DELETE CASCADE ON UPDATE NO ACTION
Scan UCC-128 In Visual Basic .NET
Using Barcode reader for .NET framework Control to read, scan read, scan image in .NET framework applications.
www.OnBarcode.com
PDF 417 Recognizer In Java
Using Barcode decoder for Java Control to read, scan read, scan image in Java applications.
www.OnBarcode.com
In the previous example, consider what happens if a customer is deleted all of the customer s orders are also deleted. This might be fine, but consider the following example:
CREATE TABLE Test.Countries ( CountryID INT PRIMARY KEY ); CREATE TABLE Test.Cities ( CityID INT PRIMARY KEY ,CountryID INT NOT NULL REFERENCES Test.Countries ON DELETE CASCADE ); CREATE TABLE Test.Customers (
Copyright © OnBarcode.com . All rights reserved.