Tutorial by Examples: d

One should have in mind that: Angular's data binding relies on JavaScript’s prototypal inheritance, thus it's subject to variable shadowing. A child scope normally prototypically inherits from its parent scope. One exception to this rule is a directive which has an isolated scope as it doesn't p...

WORKDIR /path/to/workdir The WORKDIR instruction sets the working directory for any RUN, CMD, ENTRYPOINT, COPY and ADD instructions that follow it in the Dockerfile. If the WORKDIR doesn’t exist, it will be created even if it’s not used in any subsequent Dockerfile instruction. It can be used mu...

ENV ENV <key> <value> ENV <key>=<value> ... The ENV instruction sets the environment variable <key> to the value . This value will be in the environment of all “descendant” Dockerfile commands and can be replaced inline in many as well. The ENV instruction has two...

The CMD instruction has three forms: CMD ["executable","param1","param2"] (exec form, this is the preferred form) CMD ["param1","param2"] (as default parameters to ENTRYPOINT) CMD command param1 param2 (shell form) There can only be one CMD ins...

ONBUILD [INSTRUCTION] The ONBUILD instruction adds to the image a trigger instruction to be executed at a later time, when the image is used as the base for another build. The trigger will be executed in the context of the downstream build, as if it had been inserted immediately after the FROM in...

Calculate a 6-month (126-business-day) centered moving average of a price: SELECT TradeDate, AVG(Px) OVER (ORDER BY TradeDate ROWS BETWEEN 63 PRECEDING AND 63 FOLLOWING) AS PxMovingAverage FROM HistoricalPrices Note that, because it will take up to 63 rows before and after each returned row, at...

Make sure your image object is fully loaded before you try to draw it on the canvas with context.drawImage. Otherwise the image will silently fail to display. In JavaScript, images are not loaded immediately. Instead, images are loaded asynchronously and during the time they take to load JavaScript...

When a runtime error occurs, good code should handle it. The best error handling strategy is to write code that checks for error conditions and simply avoids executing code that results in a runtime error. One key element in reducing runtime errors, is writing small procedures that do one thing. Th...

An error-handling subroutine will either: run to the end of the procedure, in which case execution resumes in the calling procedure. or, use the Resume keyword to resume execution inside the same procedure. The Resume keyword should only ever be used inside an error handling subroutine, becau...

This script, from here and here, will return all Tables and Columns where a specified value exists. This is powerful in finding out where a certain value is in a database. It can be taxing, so it is suggested that it be executed in a backup / test enviroment first. DECLARE @SearchStr nvarchar(100) ...

SELECT ps.name AS PartitionScheme , fg.name AS [FileGroup] , prv.* , LAG(prv.Value) OVER (PARTITION BY ps.name ORDER BY ps.name, boundary_id) AS PreviousBoundaryValue FROM sys.partition_schemes ps INNER JOIN sys.destination_data...

Using the Authors table in the Library Database CREATE PROCEDURE GetName ( @input_id INT = NULL, --Input parameter, id of the person, NULL default @name VARCHAR(128) = NULL --Input parameter, name of the person, NULL default ) AS BEGIN SELECT Name + ' is from ' + Country...

By Assembly Name, add library Add-Type -AssemblyName "System.Math" or by file path: Add-Type -Path "D:\Libs\CustomMath.dll" To Use added type: [CustomMath.NameSpace]::Method(param1, $variableParam, [int]castMeAsIntParam)

Directives can be used to build reusable components. Here is an example of a "user box" component: userBox.js angular.module('simpleDirective', []).directive('userBox', function() { return { scope: { username: '=username', reputation: '=reputation' }, ...

Once Powershell remoting is enabled (Enable-PSRemoting) You can run commands on the remote computer like this: Invoke-Command -ComputerName "RemoteComputerName" -ScriptBlock { Write host "Remote Computer Name: $ENV:ComputerName" } The above method creates a temporary se...

UPDATE HelloWorlds SET HelloWorld = 'HELLO WORLD!!!' WHERE Id = 5 The above code updates the value of the field "HelloWorld" with "HELLO WORLD!!!" for the record where "Id = 5" in HelloWorlds table. Note: In an update statement, It is advised to use a "where&...

A simple form of updating is incrementing all the values in a given field of the table. In order to do so, we need to define the field and the increment value The following is an example that increments the Score field by 1 (in all rows): UPDATE Scores SET score = score + 1 This can be dang...

The rep function can be used to repeat a vector in a fairly flexible manner. # repeat counting numbers, 1 through 5 twice rep(1:5, 2) [1] 1 2 3 4 5 1 2 3 4 5 # repeat vector with incomplete recycling rep(1:5, 2, length.out=7) [1] 1 2 3 4 5 1 2 The each argument is especially useful for ex...

var multiplexer = ConnectionMultiplexer.Connect("localhost"); IDatabase db = multiplexer.GetDatabase(); // intialize key with empty string await db.StringSetAsync("key", ""); // create transaction that utilize multiplexing and pipelining ITransaction transacton...

History The first computers Early computers had a block of memory that the programmer put code and data into, and the CPU executed within this environment. Given that the computers then were very expensive, it was unfortunate that it would do one job, stop and wait for the next job to be loaded in...