Skip to main content

isnull vs coalesce sql server

The ISNULL() function is used to replace NULL with the specified replacement value. This function contains only two arguments.
The ISNULL() can only have one input. So, ISNULL() is faster than COALESCE().
The ISNULL() uses the first parameter type.
The ISNULL() function is a T-SQL.

Syntax: SELECT ISNULL (NULL, 1)

The COALESCE() can have multiple inputs and it will evaluate in order until one of them is not null.
The COALESCE() function returns the first non-null value of its arguments.
The COALESCE() not limited to arguments but must be of the same data type.
The COALESCE() follows the CASE expression and returns the first non-null value.
The COALESCE() is ANSI-Standard.


Syntax:  SELECT COALESCE(NULL, NULL, 1, NULL)


Summary:

The NULL value for ISNULL() is converted to INT whereas for COAELSCE() you have to provide a type.
a)      ISNULL(NULL, NULL) — Ruturns as int
b)     COALESCE(NULL, NULL) — Ruturns an error.
c)      COALESCE(CAST(NULL as int), NULL) — Ruturns as int after cost.


The ISNULL() is a T-SQL function but The COALESCE() is ANSI-Standard.
--Example 1

DECLARE @Temp VARCHAR(3)
    SET @Temp = NULL;
SELECT ISNULL(@Temp, 'TEST') AS 'RESULT ISNULL'
SELECT COALESCE(@Temp, 'TEST') AS 'RESULT COALESCE'
-- ISNULL limited to @Temp length but COALESCE() not limited to the @Temp length
--In the above, the temp variable has length 3.So the ISNULL function returns tes and the COALESCE() function does not; depending on the length, it returns test.

--Example 2

DECLARE @Temp1 VARCHAR(4)='TEST'
DECLARE @Temp2 INT = 5
SELECT ISNULL(@Temp1, @Temp1) AS 'RESULT ISNULL'
-- Success

GO
SELECT COALESCE(@Temp1, @Temp1) AS 'RESULT COALESCE'
-- Error : Must declare the scalar variable "@Temp1".

By Anil Singh | Rating of this article (*****)

Popular posts from this blog

39 Best Object Oriented JavaScript Interview Questions and Answers

Most Popular 37 Key Questions for JavaScript Interviews. What is Object in JavaScript? What is the Prototype object in JavaScript and how it is used? What is "this"? What is its value? Explain why "self" is needed instead of "this". What is a Closure and why are they so useful to us? Explain how to write class methods vs. instance methods. Can you explain the difference between == and ===? Can you explain the difference between call and apply? Explain why Asynchronous code is important in JavaScript? Can you please tell me a story about JavaScript performance problems? Tell me your JavaScript Naming Convention? How do you define a class and its constructor? What is Hoisted in JavaScript? What is function overloadin

List of Countries, Nationalities and their Code In Excel File

Download JSON file for this List - Click on JSON file    Countries List, Nationalities and Code Excel ID Country Country Code Nationality Person 1 UNITED KINGDOM GB British a Briton 2 ARGENTINA AR Argentinian an Argentinian 3 AUSTRALIA AU Australian an Australian 4 BAHAMAS BS Bahamian a Bahamian 5 BELGIUM BE Belgian a Belgian 6 BRAZIL BR Brazilian a Brazilian 7 CANADA CA Canadian a Canadian 8 CHINA CN Chinese a Chinese 9 COLOMBIA CO Colombian a Colombian 10 CUBA CU Cuban a Cuban 11 DOMINICAN REPUBLIC DO Dominican a Dominican 12 ECUADOR EC Ecuadorean an Ecuadorean 13 EL SALVADOR

25 Best Vue.js 2 Interview Questions and Answers

What Is Vue.js? The Vue.js is a progressive JavaScript framework and used to building the interactive user interfaces and also it’s focused on the view layer only (front end). The Vue.js is easy to integrate with other libraries and others existing projects. Vue.js is very popular for Single Page Applications developments. The Vue.js is lighter, smaller in size and so faster. It also supports the MVVM ( Model-View-ViewModel ) pattern. The Vue.js is supporting to multiple Components and libraries like - ü   Tables and data grids ü   Notifications ü   Loader ü   Calendar ü   Display time, date and age ü   Progress Bar ü   Tooltip ü   Overlay ü   Icons ü   Menu ü   Charts ü   Map ü   Pdf viewer ü   And so on The Vue.js was developed by “ Evan You ”, an Ex Google software engineer. The latest version is Vue.js 2. The Vue.js 2 is very similar to Angular because Evan You was inspired by Angular and the Vue.js 2 components looks like -

nullinjectorerror no provider for httpclient angular 17

In Angular 17 where the standalone true option is set by default, the app.config.ts file is generated in src/app/ and provideHttpClient(). We can be added to the list of providers in app.config.ts Step 1:   To provide HttpClient in a standalone app we could do this in the app.config.ts file, app.config.ts: import { ApplicationConfig } from '@angular/core'; import { provideRouter } from '@angular/router'; import { routes } from './app.routes'; import { provideClientHydration } from '@angular/platform-browser'; //This (provideHttpClient) will help us to resolve the issue  import {provideHttpClient} from '@angular/common/http'; export const appConfig: ApplicationConfig = {   providers: [ provideRouter(routes),  provideClientHydration(), provideHttpClient ()      ] }; The appConfig const is used in the main.ts file, see the code, main.ts : import { bootstrapApplication } from '@angular/platform-browser'; import { appConfig } from '

React | Encryption and Decryption Data/Text using CryptoJs

To encrypt and decrypt data, simply use encrypt () and decrypt () function from an instance of crypto-js. Node.js (Install) Requirements: 1.       Node.js 2.       npm (Node.js package manager) 3.       npm install crypto-js npm   install   crypto - js Usage - Step 1 - Import var   CryptoJS  =  require ( "crypto-js" ); Step 2 - Encrypt    // Encrypt    var   ciphertext  =  CryptoJS . AES . encrypt ( JSON . stringify ( data ),  'my-secret-key@123' ). toString (); Step 3 -Decrypt    // Decrypt    var   bytes  =  CryptoJS . AES . decrypt ( ciphertext ,  'my-secret-key@123' );    var   decryptedData  =  JSON . parse ( bytes . toString ( CryptoJS . enc . Utf8 )); As an Example,   import   React   from   'react' ; import   './App.css' ; //Including all libraries, for access to extra methods. var   CryptoJS  =  require ( "crypto-js" ); function   App () {    var   data