LINQ to XML: XML Integration

LINQ to XML: XML Integration


-.NET Language-Integrated Query for XML (LINQ to XML) allows XML data to be queried by using the standard query operators as well
as tree-specific operators that provide
XPath-like navigation through descendants, ancestors, and siblings.

-It provides an efficient in-memory representation for XML that integrates with the existing System.Xml reader/writer
infrastructure and is easier to use than W3C DOM.
There are three types that do most of the work of integrating XML with queries: XName, XElement and XAttribute.

XName provides an easy-to-use way to deal with the namespace-qualified identifiers (QNames) used as both element and attribute names.
XName handles the efficient atomization of identifiers transparently and allows either symbols or plain strings to be used wherever
a QName is needed.

XML elements and attributes are represented using XElement and XAttribute respectively.
XElement and XAttribute support normal construction syntax, allowing developers to write XML expressions using a natural syntax:

var e = new XElement("Person",
new XAttribute("CanCode", true),
new XElement("Name", "Loren David"),
new XElement("Age", 31));

var s = e.ToString();

This corresponds to the following XML:


Loren David
31


XML elements can also be constructed from an existing XmlReader or from a string literal:

var e2 = XElement.Load(xmlReader);
var e1 = XElement.Parse(
@"
Loren David
31
");


XElement dovetails with the query operators, allowing developers to write queries against non-XML information and produce XML results by constructing XElements in the body of a select clause:

var query = from p in people
where p.CanCode
select new XElement("Person",
new XAttribute("Age", p.Age),
p.Name);

SQL GROUP BY Statement

SQL GROUP BY Statement:

The GROUP BY statement is used in conjunction with the aggregate functions to group the result-set by one or more columns.

SELECT Customer,SUM(OrderPrice) FROM Orders
GROUP BY Customer


GROUP BY More Than One Column

SELECT Customer,OrderDate,SUM(OrderPrice) FROM Orders
GROUP BY Customer,OrderDate

LINQ - Language-Integrated Query - Basics in C# 3.0

LINQ - Language-Integrated Query - Basics in C# 3.0


-To indicate that query is an integrated feature of the developer's primary programming languages.
-Language-integrated query allows query expressions to benefit from the rich metadata, compile-time syntax checking,
static typing and IntelliSense that was previously available only to imperative code .
-The standard query operators allow queries to be applied to any IEnumerable-based information source.
-The extensibility of the query architecture is used in the LINQ project itself to provide implementations
that work over both XML and SQL data.
-The query operators over XML (LINQ to XML) use an efficient, easy-to-use, in-memory XML facility to provide XPath/XQuery
functionality in the host programming language.

simple C# 3.0 program

using System;
using System.Linq;
using System.Collections.Generic;

class app {
static void Main() {
string[] names = { "Burke", "Connor", "Frank",
"Everett", "Albert", "George",
"Harris", "David" };

IEnumerable query = from s in names
where s.Length == 5
orderby s
select s.ToUpper();

foreach (string item in query)
Console.WriteLine(item);
}
}

Output:

BURKE
DAVID
FRANK

-The local variable query is initialized with a query expression. A query expression operates on one or more information
sources by applying one or more query operators from either the standard query operators or domain-specific operators.
This expression uses three of the standard query operators: Where, OrderBy, and Select.

Enumerable query = names
.Where(s => s.Length == 5)
.OrderBy(s => s)
.Select(s => s.ToUpper());

Single Click Selection - CheckListbox Change Property Double click to Single Click C# and VB.NET

Single Click Selection - CheckListbox Change Property Double click to Single Click

Add code at runtime

chkListBox.CheckOnClick = true;

Shrink Query in Sql Server 2008

Shrink Query in Sql Server 2008

--Use Database name
USE AdventureWorks2008R2;
GO
-- Truncate the log by changing the database recovery model to SIMPLE.
ALTER DATABASE AdventureWorks2008R2
SET RECOVERY SIMPLE;
GO
-- Shrink the truncated log file to 1 MB.
DBCC SHRINKFILE (AdventureWorks2008R2_Log, 1);
GO
-- Reset the database recovery model.
ALTER DATABASE AdventureWorks2008R2
SET RECOVERY FULL;
GO