Tutorial by Examples: u

SELECT Name FROM Customers WHERE PhoneNumber IS NULL Selection with nulls take a different syntax. Don't use =, use IS NULL or IS NOT NULL instead.

' Sometimes we don't need to evaluate all the conditions in an if statement's boolean check. ' Let's suppose we have a list of strings: Dim MyCollection as List(Of String) = New List(of String)() ' We want to evaluate the first value inside our list: If MyCollection.Count > 0 And MyCo...

' The OrElse operator is the homologous of AndAlso. It lets us perform a boolean ' comparison evaluating the second condition only if the first one is False If testFunction(5) = True OrElse otherFunction(4) = True Then ' If testFunction(5) is True, otherFunction(4) is not called. ' In...

Given this data User_IDCompletion_Date12016-07-2012016-07-2122016-07-2022016-07-2122016-07-22 ;with CTE as (SELECT *, ROW_NUMBER() OVER (PARTITION BY User_ID ORDER BY Completion_Date DESC) Row_Num FROM Data) SELECT * FORM CTE WHERE Row_Num <= n Us...

CREATE UNIQUE INDEX idx_license_id ON Person(DrivingLicenseID) WHERE DrivingLicenseID IS NOT NULL GO This schema allows for a 0..1 relationship - people can have zero or one driving licenses and each license can only belong to one person

Some functions only work on a certain type of argument: function foo(tab) return tab.bar end --> returns nil if tab has no field bar, which is acceptable --> returns 'attempt to index a number value' if tab is, for example, 3 --> which is unacceptable function kungfoo(tab) ...

A counter using an FPGA style flip-flop initialisation: module counter( input clk, output reg[7:0] count ) initial count = 0; always @ (posedge clk) begin count <= count + 1'b1; end A counter implemented using asynchronous resets suitable for ASIC synthesis: module counter...

A 2-tuple or a 3-tuple represent a group of related items. (Points in 2D space, RGB values of a color, etc.) A 1-tuple is not very useful since it could easily be replaced with a single int. A 0-tuple seems even more useless since it contains absolutely nothing. Yet it has properties that make it v...

Sitecore ships with a set of standard indexes pre-configured which you can extend, or you can define your own. Of the pre-configured, sitecore_master_index & sitecore_web_index are of most interest for your site search. These are the predefined indexes for all of your Sitecore items in the tree ...

The Scala compiler prefixes every argument in the parameter list by default with val. This means that, by default, case classes are immutable. Each parameter is given an accessor method, but there are no mutator methods. For example: case class Foo(i: Int) val fooInstance = Foo(1) val j = fooIn...

We start off with $db, an instance of the PDO class. After executing a query we often want to determine the number of rows that have been affected by it. The rowCount() method of the PDOStatement will work nicely: $query = $db->query("DELETE FROM table WHERE name = 'John'"); $count = ...

Apply will be used when when table valued function in the right expression. create a Department table to hold information about departments. Then create an Employee table which hold information about the employees. Please note, each employee belongs to a department, hence the Employee table has ref...

Below is a simple example which shows average item's price of each item per weekday. First, suppose we have a table which keeps daily records of all items' prices. CREATE TABLE tbl_stock(item NVARCHAR(10), weekday NVARCHAR(10), price INT); INSERT INTO tbl_stock VALUES ('Item1', 'Mon', 110), (...

In normal mode, we can increment the nearest number on the line at or after the cursor with <C-a> and decrement it with <C-x>. In the following examples, the cursor position is indicated by ^. Incrementing and decrementing numbers for i in range(11): ^ <C-x> decrements ...

The core idea behind the Feature Branch Workflow is that all feature development should take place in a dedicated branch instead of the master branch. This encapsulation makes it easy for multiple developers to work on a particular feature without disturbing the main codebase. It also means the mast...

The Math.random() function should give random numbers that have a standard deviation approaching 0. When picking from a deck of card, or simulating a dice roll this is what we want. But in most situations this is unrealistic. In the real world the randomness tends to gather around an common normal...

Future<Results> costlyQuery() { var completer = new Completer(); database.query("SELECT * FROM giant_table", (results) { // when complete completer.complete(results); }, (error) { completer.completeException(error); }); // this returns essentially im...

Creating and configuring Sprite and TextField objects at runtime can be costly if you are creating hundreds of thousands of these on a single frame. Therefore a common trick is "pooling" these objects for later reuse. Remember we are not just trying to optimize the creation time (new Sprit...

Working Source - https://github.com/benhysell/V.TouchIdExample Long form description - http://benjaminhysell.com/archive/2014/11/authentication-in-xamarin-ios-with-touch-id-or-passcode/ //Simple View with a switch to enable / disable Touch ID and //a button to invoke authentication /// <s...

You can create your own events and dispatch them, by extending the Event class. import flash.events.Event; class MyEvent extends Event { var data: String; static public var MY_EVENT_TYPE = "my_event_my_event_code"; public function MyEvent(type: String, data: Str...