How To Create A Postgres Database Using pgAdmin

What is a Materialized View?

Android Page refresh in 20Seconds

Android Page refresh in 20 seconds

main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/hello_world" />

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/textView1"
        android:layout_below="@+id/textView1"
        android:layout_marginLeft="23dp"
        android:text="Button" />

</RelativeLayout>

---------------------------------------------------------------------------------

MainActivity-

package com.example.pagerefresh;

import android.os.Bundle;
import android.os.Handler;
import android.app.Activity;
import android.content.Intent;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends Activity {
Handler handler;
Button b;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        b=(Button)findViewById(R.id.button1);
        
        b.setOnClickListener(new View.OnClickListener() {

@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
Toast.makeText(getApplicationContext(), "test", Toast.LENGTH_SHORT).show();
}
});
        
        Toast.makeText(getApplicationContext(), "page refreshed", Toast.LENGTH_SHORT).show();

        handler= new Handler();
      
        handler.postDelayed(new Runnable(){

            @Override
            public void run() {
                // TODO Auto-generated method stub
                Toast.makeText(getApplicationContext(), "hello1", Toast.LENGTH_SHORT).show();
              
               Intent i=new Intent(MainActivity.this,MainActivity.class);
               i.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
                 startActivity(i);
            handler.removeCallbacksAndMessages(null);
                handler.postDelayed(this, 4000);
            }

         }, 5000*4);//for 20sec
     
    }


@Override
public void onDestroy() {
    // TODO Auto-generated method stub
handler.removeCallbacksAndMessages(null);
    super.onDestroy();

   }

@Override
public void onStop() {
    // TODO Auto-generated method stub
handler.removeCallbacksAndMessages(null);
    super.onStop();

   }

}

Built-In Functions Of PostgreSQL

PostgreSQL built-in functions, also called as Aggregate functions, are used for performing processing on string or numeric data. Following is the list of all general purpose PostgreSQL built-in functions:

Functions	Description
COUNT	·         COUNT aggregate function is used to count the number of rows in a database table.
MAX	MAX aggregate function allows us to select the highest (maximum) value for a certain column.
MIN	MIN aggregate function allows us to select the lowest (minimum) value for a certain column.
AVG	·         AVG aggregate function selects the average value for certain table column.
SUM	·         SUM aggregate function allows selecting the total for a numeric column.
ARRAY	ARRAY aggregate function puts input values, including nulls, concatenated into an array.
Numeric	Complete list of PostgreSQL functions required to manipulate numbers in SQL.
String	·         Complete list of PostgreSQL functions required to manipulate strings in PostgreSQL.

MySQL vs PostgreSQL

Oracle and PostgreSQL Query Difference

10 Major Oracle and PostgreSQL Query Difference

Oracle	PostgreSQL
select * from tablename;	select * from tablename;
desc tablename	-----(select itself desc coming)
nvl(sum,0)	coalesce(sum,0)
decode(a,1,aa,bb)	(case when a=1 then aa else bb end)
oracle supports ‘’ or null (both are same)	In postgresql  ‘’ and null both are different
rownum	limit
rowed	ctid
Date shows dd/mmm/yyyy	yyyy/mmm/dd
Auto cast from String to Date	cast(d as date)
String to integer to_number(a)	cast ( a as numeric)

Installing and Setting up PostgreSQL

Oracle Vs PostgreSQL -Which is Faster?

In software industry if a project comes to engineer to develop first thing comes in his mind which language to be use. And the second and most important thing which database should use? There are several databases in market. Some are paid and reaming open source. Many people go for open source because no need to pay or invest huge amount. Oracle is the famous and most running database in market which is a paid database. PostgreSQL is similar to Oracle which is a open source database. Most of the operations of PostgreSQL are similar to Oracle.

Here I discoursed the main advantage of PostgreSQL is it is little bit faster than Oracle in fetching data. I tested with same records of data and on same machine. Here, which I found the difference.

PostgreSQL

Oracle

The same query runs in PostgreSQL in 31ms (Miliseconds) and oracle in 55ms. In Oracle if we want to check its data type we have to type a command ‘DESC TABLENAME’. But in PostgreSQL it is coming in ‘SELECT * FROM TABLE NAME’. Just see the images above.

Features Of PostgreSQL

PostgreSQL is a powerful, open source object-relational database system. Compare to oracle it fetches data quickly, And working very speed on server level. Most of all the oracle built-in functions working in PostgreSQL.

It has a strong reputation for reliability, data integrity, and correctness. It runs on all major operating systems, including Linux, UNIX (AIX, BSD, HP-UX, SGI IRIX, Mac OS X, Solaris, Tru64), and Windows. It is fully ACID compliant, has full support for foreign keys, joins, views, triggers, and stored procedures (in multiple languages). It includes most SQL:2008 data types, including INTEGER, NUMERIC, BOOLEAN, CHAR, VARCHAR, DATE, INTERVAL, and TIMESTAMP. It also supports storage of binary large objects, including pictures, sounds, or video. It has native programming interfaces for C/C++, Java, .Net, Perl, Python, Ruby, Tcl, ODBC, etc.

Features

PostgreSQL prides itself in standards compliance. Its SQL implementation strongly conforms to the ANSI-SQL:2008 standard. It has full support for subqueries (including subselects in the FROM clause), read-committed and serializable transaction isolation levels. And while PostgreSQL has a fully relational system catalog which itself supports multiple schemas per database, its catalog is also accessible through the Information Schema as defined in the SQL standard.

Data integrity features include (compound) primary keys, foreign keys with restricting and cascading updates/deletes, check constraints, unique constraints, and not null constraints.

It also has a host of extensions and advanced features. Among the conveniences are auto-increment columns through sequences, and LIMIT/OFFSET allowing the return of partial result sets. PostgreSQL supports compound, unique, partial, and functional indexes which can use any of its B-tree, R-tree, hash, or GiST storage methods.

PostgreSQL runs stored procedures in more than 12 programming languages, including Java, Perl, Python, Ruby, Tcl, C/C++, and its own PL/pgSQL, which is similar to Oracle's PL/SQL. Included with its standard function library are hundreds of built-in functions that range from basic math and string operations to cryptography and Oracle compatibility. Triggers and stored procedures can be written in C and loaded into the database as a library, allowing great flexibility in extending its capabilities. Similarly, PostgreSQL includes a framework that allows developers to define and create their own custom data types along with supporting functions and operators that define their behavior. As a result, a host of advanced data types have been created that range from geometric and spatial primitives to network addresses to even ISBN/ISSN (International Standard Book Number/International Standard Serial Number) data types, all of which can be optionally added to the system.

Source: http://www.postgresql.org/