Tutorial by Examples: e

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.

The below code will turn the table with an id of tableid into a DataTable, as well as return a DataTables API instance: $(document).ready(function() { $('#tableid').DataTable(); }); Compare this to the below code, which will turn the table into a DataTable but will not return a DataTables ...

The interface defines the behaviour that you want to expose through the DependencyService. One example usage of a DependencyService is a Text-To-Speech service. There is currently no abstraction for this feature in Xamarin.Forms, so you need to create your own. Start off by defining an interface for...

The interface you defined needs to be implemented in every targeted platform. For iOS this is done through the AVFoundation framework. The following implementation of the ITextToSpeech interface handles speaking a given text in English. using AVFoundation; public class TextToSpeechiOS : ITextToS...

After you've created and registered your platform-specific classes you can start hooking them up to your shared code. The following page contains a button that triggers the text-to-speech functionality using a pre-defined sentence. It uses DependencyService to retrieve a platform-specific implementa...

The Android specific implementation is a bit more complex because it forces you to inherit from a native Java.Lang.Object and forces you to implement the IOnInitListener interface. Android requires you to provide a valid Android context for a lot of the SDK methods it exposes. Xamarin.Forms exposes ...

' 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...

Yes, you need to SETKEY pre 1.9.6 In the past (pre 1.9.6), your data.table was sped up by setting columns as keys to the table, particularly for large tables. [See intro vignette page 5 of September 2015 version, where speed of search was 544 times better.] You may find older code making use of t...

Creating an alert dialog AlertDialog.Builder builder = new AlertDialog.Builder(Context); builder.SetIcon(Resource.Drawable.Icon); builder.SetTitle(title); builder.SetMessage(message); builder.SetNeutralButton("Neutral", (evt, args) => { // code here for handling the Neutral...

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...

First of all you need to create a class which extends RecyclerView.ItemDecoration : public class SimpleBlueDivider extends RecyclerView.ItemDecoration { private Drawable mDivider; public SimpleBlueDivider(Context context) { mDivider = context.getResources().getDrawable(R.drawable.divider_b...

Refer to the tf.slice(input, begin, size) documentation for detailed information. Arguments: input: Tensor begin: starting location for each dimension of input size: number of elements for each dimension of input, using -1 includes all remaining elements Numpy-like slicing: # x has shape...

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) ...

It is now a best-practice to use Vector instead of List because the implementations have better performance Performance characteristics can be found here. Vector can be used wherever List is used. List creation List[Int]() // Declares an empty list of type Int List.empty[Int] // U...

Note that this deals with the creation of a collection of type Map, which is distinct from the map method. Map Creation Map[String, Int]() val m1: Map[String, Int] = Map() val m2: String Map Int = Map() A map can be considered a collection of tuples for most operations, where the first e...

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 non-blocking assignment (<=) is used for assignment inside edge-sensitive always blocks. Within a block, the new values are not visible until the entire block has been processed. For example: module flip( input clk, input reset ) reg f1; reg f2; always @ (posedge clk) begin ...

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...