The predefined function execCommand() applies to the text that is selected. You can perform actions like bold, delete, redo, undo, etc. on the selected text in the editable area. You need to use the document prefix before execCommand like this document.execCommand();. exec Commands List bold copy paste cut redo undo delete superscript subscript unlink selectAll … Read more Javascript execCommand() function
Condition is a way that helps you to do the programming by applying condition constraints or lets you do programming according to your thinking. You need to know about conditional statements to work on it. There are four conditional statements in Java-script to apply condition which are the following: if condition else condition if else … Read more Conditions in JavaScript
When we want to give any message to the user or print anything on the screen as output in JavaScript then following methods are used for that- window.alert() document.write() console.log() innerHTML window.alert() Output Method Example- document.write() Output Method It replaces all the document to print its result. Example- console.log() Output Method A JavaScript object can … Read more Methods To Get Output in JavaScript
When we want to make relations between two or more tables, we take in use join operations. We are going to understand these operations with example, so first, we will create a database, table, and then insert some data in it. Database Name – jai_school Query– Create two tables – admission and fee admission table … Read more Join operations in SQL
We use LIKE operator and its wildcard with WHERE clause to search for a pattern match in a column. Wildcards to use with LIKE Wildcards Definition Example “s%” ‘S’ at First Position See “%s” ‘S’ at Second Position See “%s%” ‘S’ at Any Position See “_s%” ‘S’ at Second Position See “s%g” ‘S’ at First … Read more LIKE operator and its wildcards in SQL
HAVING clause is used to filter out records based on aggregated values. In the respect of aggregation, WHERE can’t be used. It does not work. Therefore, while applying condition where we are calculating fields data, we will use HAVING. See below example-
NOT NULL PRIMARY KEY UNIQUE FOREIGN KEY CHECK DEFAULT
This is a very simple process. For example, I have a table mobiles and this table contains a column brand. Now, I want to change the name of the column from brand to brand_name. Then, Run following command to rename the column- Do not try to change its data type like INT to VARCHAR or … Read more How To Rename a Column using SQL?
While writing a WHERE query, when you simply give column name after WHERE keyword. It means true in boolean. Understand it with example. Make a database by running query– Create a table in the database– Insert data in the table– Table Image: When you run above query, you see only NULL values are filtered if … Read more WHERE query using Boolean
If a column’s field has NULL value then it means, it is blank. This field has no value. When a column’s value is NULL then it can’t be determined by an eqal to (=) operator. The way of identifying NULL values is, you need to use IS NULL or IS NOT NULL statement. NOT NULL … Read more Handling NULL values in SQL