Tutorial by Examples: r

SUBSTR retrieves part of a string by indicating the starting position and the number of characters to extract SELECT SUBSTR('abcdefg',2,3) FROM DUAL; returns: bcd To count from the end of the string, SUBSTR accepts a negative number as the second parameter, e.g. SELECT SUBSTR('abcdefg',-4,2...

LTRIM and RTRIM remove characters from the beginning or the end (respectively) of a string. A set of one or more characters may be supplied (default is a space) to remove. For example, select LTRIM('<===>HELLO<===>', '=<>') ,RTRIM('<===>HELLO<===>', '=<>'...

Create Oracle error log table ERR$_EXAMPLE for existing EXAMPLE table: EXECUTE DBMS_ERRLOG.CREATE_ERROR_LOG('EXAMPLE', NULL, NULL, NULL, TRUE); Make writing operation with SQL: insert into EXAMPLE (COL1) values ('example') LOG ERRORS INTO ERR$_EXAMPLE reject limit unlimited;

The difference in months between two dates can be found using the MONTHS_BETWEEN( date1, date2 ): SELECT MONTHS_BETWEEN( DATE '2016-03-10', DATE '2015-03-10' ) AS difference FROM DUAL; Outputs: DIFFERENCE ---------- 12 If the difference includes part months then it will return the ...

Query: WITH generator ( value ) AS ( SELECT 1 FROM DUAL UNION ALL SELECT value + 1 FROM generator WHERE value < 10 ) SELECT value FROM generator; Output: VALUE ----- 1 2 3 4 5 6 7 8 9 10

Sample Data: CREATE TABLE table_name ( value VARCHAR2(50) ); INSERT INTO table_name ( value ) VALUES ( 'A,B,C,D,E' ); Query: WITH items ( list, item, lvl ) AS ( SELECT value, REGEXP_SUBSTR( value, '[^,]+', 1, 1 ), 1 FROM table_name UNION ALL SELECT value, ...

For creating new user, We need to follow simple steps as below : Step 1: Login to MySQL as root $ mysql -u root -p Step 2 : We will see mysql command prompt mysql> CREATE USER 'my_new_user'@'localhost' IDENTIFIED BY 'test_password'; Here, We have successfully created new user, But this u...

we can create a new controller with rails g controller command. $ bin/rails generate controller controller_name The controller generator is expecting parameters in the form of generate controller ControllerName action1 action2. The following creates a Greetings controller with an action of hell...

public class App : Application { internal static NavigationPage NavPage; public App () { // The root page of your application MainPage = new RootPage(); } } public class RootPage : MasterDetailPage { public RootPage() { var menuPage = ne...

You can use re.finditer to iterate over all matches in a string. This gives you (in comparison to re.findall extra information, such as information about the match location in the string (indexes): import re text = 'You can try to find an ant in this string' pattern = 'an?\w' # find 'an' either w...

Appearance : Happens when your script tries to send a HTTP header to the client but there already was output before, which resulted in headers to be already sent to the client. Possible Causes : Print, echo: Output from print and echo statements will terminate the opportunity to send HTTP hea...

Detailed instructions on adding the required Camel dependencies. Maven Dependency One of the most common ways to include Apache Camel in your application is through a Maven dependency. By adding the dependency block below, Maven will resolve the Camel libraries and dependencies for you. <dep...

Assume an application with a MainActivity which can call the Next Activity using a button click. public class MainActivity extends AppCompatActivity { private final String LOG_TAG = MainActivity.class.getSimpleName(); @Override protected void onCreate(Bundle savedInstanceState) { ...

The below code example will give you an adjusted version of that color where a higher percentage will be brighter and a lower percentage will be darker. Objective-C + (UIColor *)adjustedColorForColor:(UIColor *)c : (double)percent { if (percent < 0) percent = 0; CGFloat r, g, b...

We will parse the highlighted tag data through NSXMLParser We have declared few properties as follows @property(nonatomic, strong)NSMutableArray *results; @property(nonatomic, strong)NSMutableString *parsedString; @property(nonatomic, strong)NSXMLParser *xmlParser; //Fetch xml data NSURLSe...

Pan gesture recognizers detect dragging gestures. The following example adds an image to a view controller and lets the user drag it around on screen. Objective-C - (void)viewDidLoad { [super viewDidLoad]; UIImageView *imageView = [[UIImageView alloc] initWithImage:[UIImage imageNa...

Premise The most confusing thing surrounding pointer syntax in C and C++ is that there are actually two different meanings that apply when the pointer symbol, the asterisk (*), is used with a variable. Example Firstly, you use * to declare a pointer variable. int i = 5; /* 'p' is a pointer to a...

When performing tasks asynchronously there typically becomes a need to ensure a piece of code is run on the main thread. For example you may want to hit a REST API asynchronously, but put the result in a UILabel on the screen. Before updating the UILabel you must ensure that your code is run on th...

Avoid code repetition in constructors by setting a tuple of variables with a one liner: class Contact: UIView { private var message: UILabel private var phone: UITextView required init?(coder aDecoder: NSCoder) { (message, phone) = self.dynamicType.setUp() su...

@IBOutlet weak var title: UILabel! { didSet { label.textColor = UIColor.redColor() label.font = UIFont.systemFontOfSize(20) label.backgroundColor = UIColor.blueColor() } } It's also possible to both set a value and initialize it: private var loginButton = UIButton() { ...