Friday, December 30, 2011

java.sql.SQLException: ORA-03115: unsupported network datatype or representation

java.sql.SQLException: ORA-03115: unsupported network datatype or representation


I was getting the above exception when I was trying to set a CLOB data in the database using java.

More understanding about this exception can be get from

http://www.coderanch.com/t/302117/JDBC/java/java-sql-SQLException-ORA-unsupported

The mistake I was doing and getting the same exception was
While preparing the PreparedStatement Object, i was passing the query like this

pstmt = conn.prepareStatement(sqlQuery.toString());  

And while executing it, again I was giving the query in the overloaded method.

// Please note that DO NOT USE pstmt.executeUpdate(String) overloaded method   
// That will give you this exception : 
// java.sql.SQLException: ORA-03115: unsupported network datatype or representation
int rowsUpdated = pstmt.executeUpdate();  

Use the executeUpdate method without arguments and not the one with a String argument

After making this change, I didn't get this exception.

Exact root cause is still unknown to me as well.

If someone understands it better, please explain it to me as well.




Also to set the clob data in the database you can use the following

String xml= getXml();   
InputStream is = new ByteArrayInputStream(xml.getBytes());   
pstmt.setAsciiStream(++psCount, is, xml.length()); 

Thursday, December 29, 2011

How to fill a increasing values in a column of a table?

How to fill a increasing values in a column of a table?

Lets assume we have a table
Table name : test

NameValue
Yogesh0
Yogesh0
Yogesh0
Yogesh0
Yogesh0
Suresh0
Suresh0

Requirement : to insert 1, 2, 3 .... corresponding to values Yogesh

Query to Update :
create sequence seq start with 1 increment by 1;
update test set Value=seq.nextval where Name='Yogesh';
commit;

Output :
NameValue
Yogesh1
Yogesh2
Yogesh3
Yogesh4
Yogesh5
Suresh0
Suresh0

Wednesday, December 21, 2011

Classes in Javascript

Source : >http://www.phpied.com/3-ways-to-define-a-javascript-class/

3 ways to define a JavaScript class


Introduction


JavaScript is a very flexible object-oriented language when it comes to syntax. In this article you can find three ways of defining and instantiating an object. Even if you have already picked your favorite way of doing it, it helps to know some alternatives in order to read other people's code.

It's important to note that there are no classes in JavaScript. Functions can be used to somewhat simulate classes, but in general JavaScript is a class-less language. Everything is an object. And when it comes to inheritance, objects inherit from objects, not classes from classes as in the "class"-ical languages.


1. Using a function

This is probably one of the most common ways. You define a normal JavaScript function and then create an object by using the new keyword. To define properties and methods for an object created using function(), you use the this keyword, as seen in the following example.

function Apple (type) {
    this.type = type;
    this.color = "red";
    this.getInfo = getAppleInfo;
}

// anti-pattern! keep reading...
function getAppleInfo() {
    return this.color + ' ' + this.type + ' apple';
}

To instantiate an object using the Apple constructor function, set some properties and call methods you can do the following:

var apple = new Apple('macintosh');
apple.color = "reddish";
alert(apple.getInfo());

1.1. Methods defined internally

In the example above you see that the method getInfo() of the Apple "class" was defined in a separate function getAppleInfo(). While this works fine, it has one drawback – you may end up defining a lot of these functions and they are all in the "global namespece". This means you may have naming conflicts if you (or another library you are using) decide to create another function with the same name. The way to prevent pollution of the global namespace, you can define your methods within the constructor function, like this:

function Apple (type) {
    this.type = type;
    this.color = "red";
    this.getInfo = function() {
        return this.color + ' ' + this.type + ' apple';
    };
}

Using this syntax changes nothing in the way you instantiate the object and use its properties and methods.

1.2. Methods added to the prototype

A drawback of 1.1. is that the method getInfo() is recreated every time you create a new object. Sometimes that may be what you want, but it's rare. A more inexpensive way is to add getInfo() to the prototype of the constructor function.

function Apple (type) {
    this.type = type;
    this.color = "red";
}

Apple.prototype.getInfo = function() {
    return this.color + ' ' + this.type + ' apple';
};
Again, you can use the new objects exactly the same way as in 1. and 1.1.


2. Using object literals

Literals are shorter way to define objects and arrays in JavaScript. To create an empty object using you can do:
var o = {};
instead of the "normal" way:
var o = new Object();
For arrays you can do:
var a = [];
instead of:
var a = new Array();
So you can skip the class-like stuff and create an instance (object) immediately. Here's the same functionality as described in the previous examples, but using object literal syntax this time:

var apple = {
    type: "macintosh",
    color: "red",
    getInfo: function () {
        return this.color + ' ' + this.type + ' apple';
    }
}

In this case you don't need to (and cannot) create an instance of the class, it already exists. So you simply start using this instance.

apple.color = "reddish";
alert(apple.getInfo());

Such an object is also sometimes called singleton. It "classical" languages such as Java, singleton means that you can have only one single instance of this class at any time, you cannot create more objects of the same class. In JavaScript (no classes, remember?) this concept makes no sense anymore since all objects are singletons to begin with.

3. Singleton using a function

Again with the singleton, eh?

The third way presented in this article is a combination of the other two you already saw. You can use a function to define a singleton object. Here's the syntax:

var apple = new function() {
    this.type = "macintosh";
    this.color = "red";
    this.getInfo = function () {
        return this.color + ' ' + this.type + ' apple';
    };
}

So you see that this is very similar to 1.1. discussed above, but the way to use the object is exactly like in 2.

apple.color = "reddish";
alert(apple.getInfo());

new function(){...} does two things at the same time: define a function (an anonymous constructor function) and invoke it with new. It might look a bit confusing if you're not used to it and it's not too common, but hey, it's an option, when you really want a constructor function that you'll use only once and there's no sense of giving it a name.


You saw three (plus one) ways of creating objects in JavaScript. Remember that (despite the article's title) there's no such thing as a class in JavaScript. Looking forward to start coding using the new knowledge? Happy JavaScript-ing!

Tuesday, December 20, 2011

Making the input file box readonly in IE

Is it possible to prevent a user from typing in a file input text box in IE? The reason I ask is that if a user enters text that does not look like a file system path (eg. doesn't start with something like c:...) then when the user clicks the submit button nothing will happen.

I would either like to not allow the user to type in the box


SOLUTION

<input 
type="file" 
name="file" 
onKeyDown="this.blur()" 
onContextMenu="return false;">

In IE 7.0 and IE8.0 this fix is not required. As it has already been made readonly by Microsoft. This fix is specifically required for IE 6.0