Tutorial by Examples: w

Getting started with a simple map

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openlayers-3 • Getting started with openlayers-3

Using a table valued parameter to insert multiple rows to a table

First, define a used defined table type to use: CREATE TYPE names as TABLE ( FirstName varchar(10), LastName varchar(10) ) GO Create the stored procedure: CREATE PROCEDURE prInsertNames ( @Names dbo.Names READONLY -- Note: You must specify the READONLY ) AS INSERT INTO d...

Microsoft SQL Server • Table Valued Parameters

Expressing the power of 2

For expressing the power of 2 (2^n) of integers, one may use a bitshift operation that allows to explicitly specify the n. The syntax is basically: int pow2 = 1<<n; Examples: int twoExp4 = 1<<4; //2^4 int twoExp5 = 1<<5; //2^5 int twoExp6 = 1<<6; //2^6 ... int twoEx...

Java Language • Bit Manipulation

Installing PostgreSQL on Windows

While it's good practice to use a Unix based operating system (ex. Linux or BSD) as a production server you can easily install PostgreSQL on Windows (hopefully only as a development server). Download the Windows installation binaries from EnterpriseDB: http://www.enterprisedb.com/products-services-...

postgresql • Getting started with postgresql

Creating a WeakMap object

WeakMap object allows you to store key/value pairs. The difference from Map is that keys must be objects and are weakly referenced. This means that if there aren't any other strong references to the key, the element in WeakMap can be removed by garbage collector. WeakMap constructor has an optional...

JavaScript • WeakMap

Checking if an element with the key exists

To check if an element with a specified key exits in a WeakMap, use the .has() method. It returns true if it exits, and otherwise false. const obj1 = {}, obj2 = {}; const weakmap = new WeakMap([[obj1, 7]]); console.log(weakmap.has(obj1)); // true console.log(weakmap.has(obj2)); // false...

JavaScript • WeakMap

Removing an element with the key

To remove an element with a specified key, use the .delete() method. It returns true if the element existed and has been removed, otherwise false. const obj1 = {}, obj2 = {}; const weakmap = new WeakMap([[obj1, 7]]); console.log(weakmap.delete(obj1)); // true console.log(weakmap.has(obj...

JavaScript • WeakMap

Compile docker with checkpoint and restore enabled (ubuntu)

In order to compile docker its recommended you have at least 2 GB RAM. Even with that it fails sometimes so its better to go for 4GB instead. make sure git and make is installed sudo apt-get install make git-core -y install a new kernel (at least 4.2) sudo apt-get install linux-generic...

Docker • Checkpoint and Restore Containers

Using standard SQL directly with models

To use SQL syntax with model, that would transfer result to proper instantions, you should use directly one of Phalcon\Mvc\Model\Resultset classes: $users = new \Application\Models\Users(); // bitwise operation on `flag` field $sql = 'SELECT * FROM phorum.users WHERE (15 & (1 <&...

phalcon • Database Management

Show created .dll files and tables for Memory Optimized Tables

SELECT OBJECT_ID('MemOptTable1') AS MemOptTable1_ObjectID, OBJECT_ID('MemOptTable2') AS MemOptTable2_ObjectID GO SELECT name,description FROM sys.dm_os_loaded_modules WHERE name LIKE '%XTP%' GO Show all Memory Optimized Tables: SELECT name,type_desc,durability_desc,...

Microsoft SQL Server • In-Memory OLTP (Hekaton)

How do I query temporal data?

SELECT * FROM Employee FOR SYSTEM_TIME BETWEEN '2014-01-01 00:00:00.0000000' AND '2015-01-01 00:00:00.0000000' WHERE EmployeeID = 1000 ORDER BY ValidFrom;

Microsoft SQL Server • Temporal Tables

Matching a literal string with a regular expression

Sometimes you need to match a literal (sub-)string with a regular expression despite that substring containing RE metacharacters. While yes, it's possible to write code to insert appropriate backslashes to make that work (using string map) it is easiest to just prefix the pattern with ***=, which ma...

tcl • Regular Expressions

Simple, hard-coded AutoCompleteTextView

Design (layout XML): <AutoCompleteTextView android:id="@+id/autoCompleteTextView1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentTop="true" android:layout_centerHorizontal="true&...

Android • AutoCompleteTextView

Reading structures with Marshal

Marshal class contains a function named PtrToStructure, this function gives us the ability of reading structures by an unmanaged pointer. PtrToStructure function got many overloads, but they all have the same intention. Generic PtrToStructure: public static T PtrToStructure<T>(IntPtr ptr); ...

C# Language • Interoperability

Working with SYS_REFCURSOR

SYS_REFCURSOR can be used as a return type when you need to easily handle a list returned not from a table, but more specifically from a function: function returning a cursor CREATE OR REPLACE FUNCTION list_of (required_type_in IN VARCHAR2) RETURN SYS_REFCURSOR IS v_ SYS_REFCURSOR; BEGIN...

plsql • Cursors

Minimal "Hellow World" transformation

This is a minimal possible XSLT transformation. It produces the string value of the source XML document. The output format is text. Source XML document: <t>Hello, World!</t> XSLT transformation: <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/T...

xslt-1.0 • Getting started with xslt-1.0

Produce basic plots with qplot

qplot is intended to be similar to base r plot() function, trying to always plot out your data without requiring too much specifications. basic qplot qplot(x = disp, y = mpg, data = mtcars) adding colors qplot(x = disp, y = mpg, colour = cyl,data = mtcars) adding a smoother qplot(x = d...

R Language • ggplot2

Example of using a downcast on a function parameter involving subclassing

A downcast can be used to make use of a subclass's code and data inside of a function taking a parameter of its superclass. class Rat { var color = "white" } class PetRat: Rat { var name = "Spot" } func nameOfRat(🐭: Rat) -> String { guard let petRat = ...

Swift Language • Type Casting

Iterating over the entries of a hash table with loop

The loop macro supports iteration over the keys, the values, or the keys and values of a hash table. The following examples show possibilities, but the full loop syntax allows more combinations and variants. Over keys and values (let ((ht (make-hash-table))) (setf (gethash 'a ht) 1 (g...

common-lisp • Hash tables

Iterating over the entries of a hash table with a hash table iterator

The keys and values of a hash table can be iterated over using the macro with-hash-table-iterator. This may be a bit more complex than maphash or loop, but it could be used to implement the iteration constructs used in those methods. with-hash-table-iterator takes a name and a hash table and binds...

common-lisp • Hash tables