Hello everybdoy,

today I want to write some notes about hierarchy research in ms sql database. 

Imagine you have following structure in your table 

TableWithParentChild:

id               |           rootID   |     some additional fields

1                |            1          |      ----

2                |            1          |      ----

3                |            2          |      ----

4                |            2          |      ----

5                |            2          |      ----

and image that you need to get info like who is below 1. 

for this purpose following sql can be useful:

-- wrap up tree selection into tvf
create function HierarchyFunction(@parentID int)
returns table
as
return
with tree
as
(select id,  rootID from TableWithParentChild
         where id = @parentID
         union all
         select p.id, p.rootID from TableWithParentChild as P
         join tree on tree.id = P.rootID
         and P.id != P.rootID
)
select * from tree

select p.* from  TableWithParentChild as p
join HierarchyFunction(1) as tree
on p.id = tree.id

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Hello everybody,

some sql notes:

dbcc freeproccache; this one will clean plan of cached of sql.

Another note of how to find Sql code and plan by id from dm_exec_cached_plans

create function SqlAndPlan(@handle varbinary(max))

returns table

as

return select sql.text, cp.usecounts,cp.cacheobjtype,

cp.objtype, cp.size_in_bytes,

qp.query_plan

 from

 sys.dm_exec_sql_text(@handle) as sql cross join

 sys.dm_exec_query_plan(@handle) as qp

 join sys.dm_exec_cached_plans as cp

 on cp.plan_handle = @handle;

then you can use it in the following way:

 select * from SqlAndPlan(0x06650D007852A00B40613C82000000000000000000000032)

And in order to see sql and plan simultanously you can use following view:

create view PlanCache

as

select sp.* from sys.dm_exec_cached_plans   as cp

cross apply SqlAndPlan(cp.plan_handle) as sp

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Hello everybody,

some MS SQL internals.

Imagine, you want to see what MS SQL cached. How you can do it? One of the ways is to look into sys.dm_exec_cached_plans. 

For example like this:

select * from sys.dm_exec_cached_plans

this code will return to you all what is cached in your MS-SQL database. Most probably result will puzzle you. What to do with all of it?

Take look at the screenshot :

the area of interest for us is column plan_handle. 

You can use it for another sql request. Like this:

select * from sys.dm_exec_query_plan(0x06000C002D51D1304021F8AE000000000000000000000000);

if you click at column with xml you'll see the following picture:

How to interpret those results? I hope to describe in one of other notes on my blog.

For now another question, how to see the text of cached value? 

You can do it with another sql 

for example like this:

select * from sys.dm_exec_sql_text(0x06000C002D51D1304021F8AE000000000000000000000000)

in the column text you'll see column text which will represent what MS SQL cached. In my case it is following text:

select [first name], [last name], dense_rank() over (order by [last name]) as rn from employees

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Hello everybody,

today I want to write few words about Moq and unit testing. 

First of all you can have a question, why do I need Moq at all?

Moq is especially useful for cases if we don't have desire to code interface, then code implementation of interface, and then code fake implementation. As usually those simple implementation are relatively simple so somebody ( as Moq team ) can organize code generation for your simple interface implementations.

So, unit test is something that should follow 3 A:

1. Arrange
2. Act
3. Assert

General schema of Unit test implementation can be like this:

        [Test]
        public void SomeTest()
        {
            //Arrange
            var mockRepository = new Mock<IBaseInterface>();
            mockRepository.Setup(x => x.FunctionInIBaseInterface(It.IsAny<SomeClass>()));
            
            var classWhichUsesImplementationOfinterface = new ClassWhichUsesImplementationOfinterface (mockRepository.Object);

            //Act
            classWhichUsesImplementationOfinterface.Create(new SomeClassWithEmptConstructor());

            //Assert
            mockRepository.VerifyAll();
        }            

The most intersting part for me was mockRepository.Setup(x => x.FunctionInIBaseInterface(It.IsAny<SomeClass>())); Setup here can be considered as saying: setup this expectation.  This code arranges setup for a calling to a void method. But void method inside of it should call function FunctionInIBaseInterface.  In other case unit test will fail.

How many times some function was executed. 

 someRepository.Verify(x=>x.SomeFunction(It.IsAny<SomeClass>()), Times.Exactly(5));

This code will check that SomeFunction was executed exactly 5 times and it expects instane of any SomeClass class.

Another usefull functions for unit testing

Setup function after dot has interesting list. 

I'll mention them from simplest ( from my viewpoint ) to most complicated.

mockRepository

                    .Setup(x => x.TryParse(It.IsAny<string>(), out address))

                    .Returns(true);

this setup will configure expectation that function TryParse will be executed and expects that function TryParse will return true.

In order to execute it your implementation should call this function.

Very surprising is usage of Callback. Look at this code:

var i = 1;

mockIdFactory.Setup(x => x.Create())

       .Returns(() => i)

       .Callback(() => i++);

This code will cause passing Create vales for mockIdFactory not just one value, but ints which will be incremented one by one.

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Hello everybody,

today I want to write some moments about bootstrap.

If to speak in general bootstrap is beast which has some javascript and css code. 

One of the ways to modify behaviour of bootstrap is to add reference to bootstrap style, and then add reference to your customization of css in which you can change boostrap settings with overriding basic bootstrap code. For example you can achieve it in the following way:

<link rel="stylesheet" href="css/bootstrap.min.css">
<link rel="stylesheet" href="css/yourCustomized.css">

One more interested features of bootstrap is grid layout of something. 
If in your html you'll write something like this:

<section id="body" class="container">

then you section body will have 12 cells. And you can manage postion and size of cell with help of bootstrap classes. 

The following options are awailable:

• col-lg-* - screens which are wider or equal then 1200 px
• col-md-* screens which are wider or equal then 992 px
• col-sm-* screens which are wider or equal then 768 px
• col-xs-* screens which are smaller or equal then 768 px

Another interesting feature is building architecute of bootstrap. It is build with mobile first approach. If to put simply it means that it was built initially for mobile devices with small screens ( screen smaller then 768 px ), then with bigger ( more then 768 px ), more bigger ( more then 992 px ) and large ( more then 1200 px ). Try to guess from which style life of bootstrap started?

So, what is value of all of this staff?

One of the most interesting features is option of defining look and feel of your "cells" at each platform.

For example you can write something that will be applied to four platform for which bootstrap was initially builted:

class="col-lg-3 col-md-6 col-sm-4 col-xs-3"

That statement will be interpreted in the following way:

locate item with that class as third column on large screen, as six column on middle screen at fourth column at small screen and as thir column at extra small screen.

Other usefull classes of bootstrap which are particularly useful for images:

pull-left - locate image with binding to left side

pull-right - locate image with binding to right side

img-thumbnail - display image as thumbnail instead of displaying at as full size image

hidden-md - don't display image at middle size screen

visible-md - always display image at middle size screen.

Very usefull site bootswatch.com - it has free bootstrap themes, which you can use for free without fear of court suit against you.

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Hello everybody.

Today I want to give some demo.

using System;
using System.Diagnostics;

namespace StackOverflowQuest
{
    class Program
    {
        struct StructTest
        {
            public string TestString { get; set; }

            //public override bool Equals(object obj)
            //{
            //    var ct = (StructTest)obj;
            //    return ct.TestString == this.TestString;
            //}
        }
        class ClassTest
        {
            public string TestString { get; set; }

            public override bool Equals(object obj)
            {
                var ct = obj as ClassTest;
                if (ct == null)
                    return false;
                return ct.TestString == this.TestString;
            }
        }

        static void Main(string[] args)
        {
            StructTest st = new StructTest() { TestString = "water"};
            StructTest st2 = new StructTest() { TestString = "water" };

            ClassTest ct1 = new ClassTest() { TestString = "water" };
            ClassTest ct2 = new ClassTest() { TestString = "water" };

            int numberOfIterations = 500000;

            Stopwatch sw2 = new Stopwatch();
            sw2.Start();
            for (int i = 0; i < numberOfIterations; i++)
            {
                ct1.Equals(ct2);
            }
            sw2.Stop();
            Console.WriteLine("class perfomance = {0} Elapsed Milliseconds", sw2.ElapsedMilliseconds);

            Stopwatch sw1 = new Stopwatch();
            sw1.Start();
            for(int i = 0; i < numberOfIterations; i++)
            {
                st.Equals(st2);
            }
            sw1.Stop();
            Console.WriteLine("structs perfomance = {0}  Elapsed Milliseconds", sw1.ElapsedMilliseconds);
            Console.ReadKey();
        }
    }
}

Take note of commented method of Equals method. If I execute that code on my machine, I'm getting difference in perfomance in 6 times. But if to uncomment Equals, then class and struct have comparable perfomance.

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Hello everybody,

today I want to share one trick which can save you few lines of code.

Imagine case: you created graph, and want to read something from db, and then set current property of that graph view to some value. How to do it in one line? The anser is simple, with help of Search<>

For example it can be like this:

public PXSelectOrderBy<SalesOrder, OrderBy<Asc<SalesOrder.orderNbr>>> Orders;
...
graph.Orders.Current = graph.Orders.Search<SalesOrder.orderNbr>(order.OrderNbr);

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Hello everybody,

today I want to write about reflecting hierarchy of classes in db with help of code-first.

There are three types: 

1. Table per Hierarchy
2. Table per Type
3. Table per conreate class.

Below goes more detailed description

• Table per Hierarchy (TPH): one table for the entire class inheritance hierarchy. Table includes discriminator column which distinguishes between inheritance classes. This is a default inheritance mapping strategy in Entity Framework.
• Table per Type (TPT): This approach suggests a separate table for each domain class.
• Table per Concrete class (TPC): one table for one concrete class, but not for the abstract class. So, if you inherit the abstract class in multiple concrete classes, then the properties of the abstract class will be part of each table of the concrete class.

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Hello everybody,

today I want to share my usage if IDisposable interface in C#.

Before code presentation some explanations:

1. If created by me class uses some unmanaged resources then it means that I should also implement IDisposable interface in order to clean memory. 
2. Clean objects as soon as I finished usage of it. 
3. In my dispose method I iterate over all IDisposable members of class and call Dispose.
4. In my Dispose method call GC.SuppressFinalize(this) in order to notify garbage collector that my object was already cleaned up. I do it because calling of GC is expensive operation.
5. As additional precaution I try to make possible calling of Dispose() multiple times.
6. Sometime I add private member _disposed and check in method calls did object was cleaned up. And if it was cleaned up then generate ObjectDisposedException 

public class SomeClass : IDisposable
        {
            /// <summary>
            /// As usually I don't care about it
            /// </summary>
            public void SomeMethod()
            {
                if (_disposed)
                    throw new ObjectDisposedException("SomeClass instance been disposed");
            }

            public void Dispose()
            {
                Dispose(true);
            }

            private bool _disposed;

            protected virtual void Dispose(bool disposing)
            {
                if (_disposed)
                    return;
                if (disposing)//we are in the first call
                {
                }
                _disposed = true;
            }
        }

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Hello everybody,

Here is just shorp version of application which searches for duplicates in folder.

In  downloadable archive you can find my implementation of searcher with Task, ContinueWith and some other new features of C# 4.5

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