c# data matrix generator DATA ACCESS LAYER SERVICES in C#

Encoder Data Matrix in C# DATA ACCESS LAYER SERVICES

Clearly, none of the earlier solutions are ideal. What you need is a way to store XML data in its native form while also providing indexing and querying capabilities on any part of the data. This is exactly what SQL Server 2005 provides with the new XML native type and an integrated XML query language called XQuery.

Since XML is a native type like int, varchar, etc., adding an XML column to a table is the same as adding any other type of column. For example, the following script creates a table with an XML column: CREATE TABLE Customer( CustomerId int NOT NULL, CustomerData xml NOT NULL, ) This script creates a Customer table with two fields: CustomerId and CustomerData. Notice that CustomerData is typed as an XML column. You can also define XML typed parameters in stored procedures. Again, as the following example shows, simply define it like any other type of parameter: CREATE PROCEDURE SaveCustomer( @CustData xml ) AS --- stored proc code ... GO

Untyped XML vs. Typed XML The XML column created in the previous example is referred to as an untyped XML column because you did not associate an XML Schema. An untyped XML column can hold any wellformed XML document or fragment. This is useful if the column must accept several different types of XML documents or you do not have prior knowledge of the schema. SQL Server checks for well formedness before accepting XML into an untyped XML column, but it cannot validate the XML without an associated schema. Although untyped XML columns are flexible, if possible, you should define a typed XML column by associating an XML Schema. This enables SQL Server to perform validation and optimize storage and queries. The following CREATE script demonstrates how to define a typed XML column: CREATE TABLE Customer( CustomerID int, CustomerData xml (CustomerSchemaCollection) ) As this example shows, you specify the schema information after the xml type keyword. SQL Server 2005 uses schema collections to contain and manage sets of related schemas. So for this to work, you must first define the customer schema and import the schema into CustomerSchemaCollection. The following example demonstrates this:

CREATE XML SCHEMA COLLECTION CustomerSchemaCollection AS N'< xml version="1.0" encoding="utf-16" > <!-- Put your schema here! --> </xs:schema>'; Content vs. Document Storage Typed XML columns come in two varieties: content and document. Surprisingly, the default is content, which means that a column can store XML with multiple top-level elements. To explicitly define content storage, specify it when declaring the XML column: CREATE TABLE Customer( CustomerID int, CustomerData xml (CONTENT CustomerSchemaCollection) ) Alternatively, you can constrain the XML column to accept only XML documents that have a single top-level element. You do this using the DOCUMENT keyword, as we shown in the following example: CREATE TABLE Customer3( CustomerID int, CustomerData xml (DOCUMENT CustomerSchemaCollection) )

Much like an object, the XML data type exposes several methods you can use to query and modify the XML data. These methods are listed in Table 11-8. Table 11-8. XML Data Type Methods

Executes a given XQuery expression on the contained XML and returns the result as an instance of XML type. Executes a given XQuery expression on the contained XML and converts the result to a given SQL type (such as int, varchar, etc.) The XQuery expression must return a scalar value. Executes a given XQuery expression on the contained XML and returns 1 (representing true) if the query finds at least one matching XML node. Otherwise the method returns 0 (representing false). Updates the contained XML according to the given XML Data Manipulation Language (XML DML) expression. Executes the given XQuery expression on the contained XML and returns the resulting nodes as a rowset. This is useful for shredding an XML document in to relational tables.