Sunday, 22 March 2015

Difference between inner join and outer join in MySQL

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




Saturday, 21 March 2015

How can I get query string values in JavaScript and jQuery?

How can I get query string values in JavaScript and jQuery?

I want to get the values from the Query String (means from URL), values are dynamic but query string variable is constant.

Suppose, I have following URL:
http://www.example.com/country.php?id=10&c=country

Now, I want to get the value of following query string.
id //currently it is 10, but it is dynamic.
c //currently it is country, but it is dynamic.


Solution 1: Get the value of query string with JavaScript.
Step 1: Add following javaScript function in your page.
   
function getParam(name) {
    name = name.replace(/[\[]/, "\\[").replace(/[\]]/, "\\]");
    var regex = new RegExp("[\\?&]" + name + "=([^&#]*)"),
        result = regex.exec(location.search);
    return result === null ? "" : decodeURIComponent(result[1].replace(/\+/g, " "));
}

Step 2: Use getParam function to get the query string values. See below:
console.log(getParam('id'));
console.log(getParam('c'));



Solution 2: Get the value of query string with jQuery.
Step 1: Add jQuery File in your webpage.
<script src="//code.jquery.com/jquery-1.11.2.min.js"></script>

Step 2: Add following jQuery function in web page.
jQuery(document).ready(function(){
  $.getParamJquery = function(name, url) {
      if (!url) {
       url = window.location.href;
      }
      var results = new RegExp('[\\?&]' + name + '=([^&#]*)').exec(url);
      if (!results) { 
          return undefined;
      }
      return results[1] || undefined;
  }
  
});

Step 3: Use getParamJquery function to get the query String values. See below:
jQuery(document).ready(function(){
  console.log($.getParamJquery('id'));   
  console.log($.getParamJquery('c'));
}