Tutorial by Examples: g

This query selects all employees not on the Supervisors table. SELECT * FROM Employees WHERE EmployeeID not in (SELECT EmployeeID FROM Supervisors) The same results can be achieved using a LEFT JOIN. SELECT * FROM Employees AS e LEFT JOIN Supervisors AS s ON s.E...

Definition : When multiple methods with the same name are declared with different parameters, it is referred to as method overloading. Method overloading typically represents functions that are identical in their purpose but are written to accept different data types as their parameters. Factors af...

Jasmine can spy on an existing function using the spyOn function. let calculator = { multiply: function(a, b) { return a * b; }, square: function(a) { return this.multiply(a, a); } } describe('calculator', function() { it('squares numbers by multiplying them by the...

We can use jasmine.createSpy() to create a standalone spy. This is often useful if we need to pass a function as a callback to another function and want to test how it is used. // source code function each(arr, fn) { arr.forEach(fn); } // test code describe('each', function() { let m...

The NSDate class provides methods for creating NSDate objects corresponding to a given date and time. An NSDate can be initialized using the designated initializer, which: Returns an NSDate object initialized relative to 00:00:00 UTC on 1 January 2001 by a given number of seconds. NSDate *date...

We can match on lists like any other data type, though they are somewhat unique, in that the constructor for building up lists is the infix function ::. (See the example Creating a list for more on how that works.) matchMyList : List SomeType -> SomeOtherType matchMyList myList = case myL...

If you're ever dealing with C Binary API's from Perl Code, via the syscall, ioctl, or fcntl functions, you need to know how to construct memory in a C Compatible way. For instance, if you were ever dealing with some function that expected a timespec, you'd look into /usr/include/time.h and find: s...

The procedure describes how to add an Object library reference, and afterwards how to declare new variables with reference to the new library class objects. The example below shows how to add the PowerPoint library to the existing VB Project. As can be seen, currently the PowerPoint Object library...

String literals imply no escaping or interpolation ( with the exception of quoting string terminators ) print 'This is a string literal\n'; # emits a literal \ and n to terminal print 'This literal contains a \'postraphe '; # emits the ' but not its preceding \ You can use alternative quoting...

Double-quoted strings use interpolation and escaping – unlike single-quoted strings. To double-quote a string, use either double quotes " or the qq operator. my $greeting = "Hello!\n"; print $greeting; # => Hello! (followed by a linefeed) my $bush = "They misunderestimat...

We have a sample Spring boot application which stores user data in MongoDB and we are using Rest services to retrieve data First there is a domain class i.e. POJO @Document public class User{ @Id private String id; private String name; } A corresponding repository based on ...

import pandas as pd import io temp=u"""index; header1; header2; header3 1; str_data; 12; 1.4 3; str_data; 22; 42.33 4; str_data; 2; 3.44 2; str_data; 43; 43.34 7; str_data; 25; 23.32""" #after testing replace io.StringIO(temp) to filename df = pd.read_csv(io....

A common pitfall of child classes is that, if your parent and child both contain a constructor(__construct()) method, only the child class constructor will run. There may be occasions where you need to run the parent __construct() method from it's child. If you need to do that, then you will need to...

To support a given application, you often create a new role and database to match. The shell commands to run would be these: $ createuser -P blogger Enter password for the new role: ******** Enter it again: ******** $ createdb -O blogger blogger This assumes that pg_hba.conf has been prope...

If we know the length of the string, we can use a for loop to iterate over its characters: char * string = "hello world"; /* This 11 chars long, excluding the 0-terminator. */ size_t i = 0; for (; i < 11; i++) { printf("%c\n", string[i]); /* Print each character of ...

In C, a string is a sequence of characters that is terminated by a null character ('\0'). We can create strings using string literals, which are sequences of characters surrounded by double quotation marks; for example, take the string literal "hello world". String literals are automatica...

An array of strings can mean a couple of things: An array whose elements are char *s An array whose elements are arrays of chars We can create an array of character pointers like so: char * string_array[] = { "foo", "bar", "baz" }; Remember: w...

In the Project.pro file we add : CONFIG += sql in MainWindow.h we write : #include <QMainWindow> #include <QSql> #include <QDebug> namespace Ui { class MainWindow; } class MainWindow : public QMainWindow { Q_OBJECT public: explicit MainWindow(QWid...

In the Project.pro file we add : CONFIG += sql in MainWindow.h we write : #include <QMainWindow> #include <QSql> #include <QDebug> namespace Ui { class MainWindow; } class MainWindow : public QMainWindow { Q_OBJECT public: explicit MainWindow(QWidget...

In the Project.pro file we add : CONFIG += sql in MainWindow.h we write : #include <QMainWindow> #include <QSql> #include <QDebug> namespace Ui { class MainWindow; } class MainWindow : public QMainWindow { Q_OBJECT public: explicit MainWindow(QWidget...