Tutorial by Examples: u

From MSDN: An enumeration type (also named an enumeration or an enum) provides an efficient way to define a set of named integral constants that may be assigned to a variable. Essentially, an enum is a type that only allows a set of finite options, and each option corresponds to a number. By d...

To duplicate a table, simply do the following: CREATE TABLE newtable LIKE oldtable; INSERT newtable SELECT * FROM oldtable;

WITH CTE (StudentId, Fname, LName, DOB, RowCnt) as ( SELECT StudentId, FirstName, LastName, DateOfBirth as DOB, SUM(1) OVER (Partition By FirstName, LastName, DateOfBirth) as RowCnt FROM tblStudent ) SELECT * from CTE where RowCnt > 1 ORDER BY DOB, LName This example uses a Common Table ...

Match any: Must match at least one string. In this example the product type must be either 'electronics', 'books', or 'video'. SELECT * FROM purchase_table WHERE product_type LIKE ANY ('electronics', 'books', 'video'); Match all (must meet all requirements). In this example both 'united...

CREATE SEQUENCE orders_seq START WITH 1000 INCREMENT BY 1; Creates a sequence with a starting value of 1000 which is incremented by 1.

a reference to seq_name.NEXTVAL is used to get the next value in a sequence. A single statement can only generate a single sequence value. If there are multiple references to NEXTVAL in a statement, they use will use the same generated number. NEXTVAL can be used for INSERTS INSERT INTO Orders (Or...

Add days into a dateTime object. DateTime today = DateTime.Now; DateTime answer = today.AddDays(36); Console.WriteLine("Today: {0:dddd}", today); Console.WriteLine("36 days from today: {0:dddd}", answer); You also can subtract days passing a negative value: DateTime today...

double[] hours = {.08333, .16667, .25, .33333, .5, .66667, 1, 2, 29, 30, 31, 90, 365}; DateTime dateValue = new DateTime(2009, 3, 1, 12, 0, 0); foreach (double hour in hours) Console.WriteLine("{0} + {1} hour(s) = {2}", dateValue, hour, ...

string dateFormat = "MM/dd/yyyy hh:mm:ss.fffffff"; DateTime date1 = new DateTime(2010, 9, 8, 16, 0, 0); Console.WriteLine("Original date: {0} ({1:N0} ticks)\n", date1.ToString(dateFormat), date1.Ticks); DateTime date2 = date1.AddMilliseconds(1); Console....

Once the instance of the BackgroundWorker has been declared, it must be given properties and event handlers for the tasks it performs. /* This is the backgroundworker's "DoWork" event handler. This method is what will contain all the work you wish to have your progra...

This allows the BackgroundWorker to be cancelled in between tasks bgWorker.WorkerSupportsCancellation = true; This allows the worker to report progress between completion of tasks... bgWorker.WorkerReportsProgress = true; //this must also be used in conjunction with the ProgressChanged event...

A BackgroundWorker is commonly used to perform tasks, sometimes time consuming, without blocking the UI thread. // BackgroundWorker is part of the ComponentModel namespace. using System.ComponentModel; namespace BGWorkerExample { public partial class ExampleForm : Form { ...

The following example demonstrates the use of a BackgroundWorker to update a WinForms ProgressBar. The backgroundWorker will update the value of the progress bar without blocking the UI thread, thus showing a reactive UI while work is done in the background. namespace BgWorkerExample { public...

A good use of extension method is to make the language more functional Sub Main() Dim strings = { "One", "Two", "Three" } strings.Join(Environment.NewLine).Print() End Sub <Extension> Public Function Join(strings As IEnumerable(Of String), separa...

Installing linq-to-sql: Right-click the App_Code folder and then click Add New Item. The Add New Item dialog box is displayed. Under Visual Studio installed templates, select the LINQ to SQL Classes template and rename the file Tasks.dbml. Click Add. OR: Under VS2102, in your solution explorer, r...

Create a DataFrame of random numbers: import numpy as np import pandas as pd # Set the seed for a reproducible sample np.random.seed(0) df = pd.DataFrame(np.random.randn(5, 3), columns=list('ABC')) print(df) # Output: # A B C # 0 1.764052 0.400157 0.9787...

Multi-line code comments are wrapped in /* ... */: /* This query returns all employees */ SELECT * FROM Employees It is also possible to insert such a comment into the middle of a line: SELECT /* all columns: */ * FROM Employees

As Handlers are used to send Messages and Runnables to a Thread's message queue it's easy to implement event based communication between multiple Threads. Every Thread that has a Looper is able to receive and process messages. A HandlerThread is a Thread that implements such a Looper, for example th...

#You can use pattern matching to run different #functions based on which parameters you pass #This example uses pattern matching to start, #run, and end a recursive function defmodule Counter do def count_to do count_to(100, 0) #No argument, init with 100 end def ...

Creating a DB and a Table DROP DATABASE IF EXISTS books_db; CREATE DATABASE books_db WITH ENCODING='UTF8' TEMPLATE template0; DROP TABLE IF EXISTS books; CREATE TABLE books ( id SERIAL PRIMARY KEY, client TEXT NOT NULL, data JSONb NOT NULL ); Populating the DB INSERT INTO books...