Web Technology Experts Notes

Monday, 23 March 2015

How to Include a JavaScript file in another JavaScript file?

Including a javascript file in another javascript file is common in web development.
Because many times we include the javascript file at run time on the behalf of some conditions.

So, we can achieve this using javascript as well as using jQuery.

Method 1: Use JavaScript to include another JavaScript file.
Step 1: Add following function in web page.

function loadScript(url)
{    
    var head = document.getElementsByTagName('head')[0];
    var script = document.createElement('script');
    script.type = 'text/javascript';
    script.src = url;
    head.appendChild(script);
}

Step 2:just call the below loadScript function, Where you want to include the js file.

 loadScript('/js/jquery-1.7.min.js');

Method 2: Use jQuery to include another javasScript file .
Step 1: Add jQuery File in your webpage.
<script src="//code.jquery.com/jquery-1.11.2.min.js"></script> Step 2: Just call the getScript function functions.

 jQuery(document).ready(function(){
    $.getScript('/js/jquery-1.7.min.js');
});

Sunday, 22 March 2015

Difference between inner join and outer join in MySQL

Joins are used to get the records from two OR more tables. Following are different type of joins used in mysql.

Left Join
Right Join
Inner Join
Self Join
Outer Join

Following are difference between Inner Join & Outer Join.

Inner Join: It is used to get the common records from two table or more tables.

MySQL Inner Join Example:

SELECT * FROM `geo_cities` as gc INNER JOIN meta_data AS md on md.city_id=gc.id;

Outer Join: It is used to get the all records from two tables or more tables.

MySQL Outer Join Example:
MySQL does not provide the FULL JOIN.
You need to UNION the result of Right Join and Left Join from both tables.

SELECT * FROM `geo_cities` as gc LEFT JOIN meta_data AS md on md.city_id=gc.id
UNION
SELECT * FROM `geo_cities` as gc RIGHT JOIN meta_data AS md on md.city_id=gc.id