Tutorial by Examples: er

You can insert multiple rows in the database at the same time: INSERT INTO person (name, age) VALUES ('john doe', 25), ('jane doe', 20);

You can insert data in a table as the result of a select statement: INSERT INTO person SELECT * FROM tmp_person WHERE age < 30; Note that the projection of the select must match the columns required for the insert. In this case, the tmp_person table has the same columns as person.

Beware that numbers can accidentally be converted to strings or NaN (Not a Number). JavaScript is loosely typed. A variable can contain different data types, and a variable can change its data type: var x = "Hello"; // typeof x is a string x = 5; // changes typeof x to...

When custom options are merged, they use the default strategy, which simply overwrites the existing value. If you want a custom option to be merged using custom logic, you need to attach a function to Vue.config.optionMergeStrategies: Vue.config.optionMergeStrategies.myOption = function (toVal, fro...

When a mixin and the component itself contain overlapping options, they will be “merged” using appropriate strategies. For example, hook functions with the same name are merged into an array so that all of them will be called. In addition, mixin hooks will be called before the component’s own hooks:...

Let's say you have a service the same as the one defined in the "First service and host" example. To create a client, define the client configuration section in the system.serviceModel section of your client configuration file. <system.serviceModel> <services> <cli...

It was common practice to use NSRunLoop to show modal UIAlertView to block code execution until user input is processed in iOS; until Apple released the iOS7, it broke few existing apps. Fortunately, there is a better way of implementing it with C#’s async/await. Here’s the new code taking advantag...

Input table data (People table) IdNameAge1John232Jane31 Query SELECT Id, Name, Age FROM People FOR JSON PATH Result [ {"Id":1,"Name":"John","Age":23}, {"Id":2,"Name":"Jane","Age":31} ]

(let [x true y true z true] (match [x y z] [_ false true] 1 [false true _ ] 2 [_ _ false] 3 [_ _ true] 4)) ;=> 4

(match [['asymbol]] [['asymbol]] :success) ;=> :success

C++11 NOTE: std::auto_ptr has been deprecated in C++11 and will be removed in C++17. You should only use this if you are forced to use C++03 or earlier and are willing to be careful. It is recommended to move to unique_ptr in combination with std::move to replace std::auto_ptr behavior. Before we ...

Some API calls return a single failure/success flag, without any additional information (e.g. GetObject): if ( GetObjectW( obj, 0, NULL ) == 0 ) { // Failure: no additional information available. }

In addition to a failure/success return value, some API calls also set the last error on failure (e.g. CreateWindow). The documentation usually contains the following standard wording for this case: If the function succeeds, the return value is <API-specific success value>. If the function...

Some API calls can succeed or fail in more than one way. The APIs commonly return additional information for both successful invocations as well as errors (e.g. CreateMutex). if ( CreateMutexW( NULL, TRUE, L"Global\\MyNamedMutex" ) == NULL ) { // Failure: get additional information. ...

HRESULTs are numeric 32-bit values, where bits or bit ranges encode well-defined information. The MSB is a failure/success flag, with the remaining bits storing additional information. Failure or success can be determined using the FAILED or SUCCEEDED macros. HRESULTs are commonly used with COM, but...

The . operator in Rust comes with a lot of magic! When you use ., the compiler will insert as many *s (dereferencing operations) necessary to find the method down the deref "tree". As this happens at compile time, there is no runtime cost of finding the method. let mut name: String = &quo...

CSS body { counter-reset: item-counter; } .item { counter-increment: item-counter; } .item:before { content: counter(item-counter, upper-roman) ". "; /* by specifying the upper-roman as style the output would be in roman numbers */ } HTML <div class='item'>Item...

CSS body { counter-reset: item-counter; /* create the counter */ } .item { counter-increment: item-counter; /* increment the counter every time an element with class "item" is encountered */ } .item-header:before { content: counter(item-counter) ". "; /* print the v...

function createNewFolderInGoogleDrive(folderName) { return DriveApp.createFolder(folderName); } Use function createNewFolderInGoogleDrive to create folder named Test folder in a Google Drive root: var newFolder = createNewFolderInGoogleDrive('Test folder'); newFolder has Class Folder typ...

A HTTP 500 Internal Server Error is a general message meaning that the server encountered something unexpected. Applications (or the overarching web server) should use a 500 when there's an error processing the request - i.e. an exception is thrown, or a condition of the resource prevents the proces...