What is Decode?

[Shahir Deo]

Hi Guys ,


What is Decode in Oracle?


Like : decode(?,null,id,?)

What Condition is This? and What does it return?

[Luk Lukach]

Your question is very abstract. There are many ways to encode information, eventually the encoded information will look differently after encoding.
There are character encoding techniques such as UTF8 UTF16 ASCII etc and there are binary-text encoding techniques such as Base64

I would recommend you to read the JavaDoc of the method you specified and see which encoding it uses.

[Tim Cooke]

Plenty of resources available for this function, like here and here. Any particular aspect of this function that you don't understand?

[Shahir Deo]

Tim Cooke wrote:Plenty of resources available for this function, like here and here. Any particular aspect of this function that you don't understand?

As i Have Given the Example,

I need to Understand, What it return and what was the Condition.

decode(?,null,id,?)

In the Java Code, We are setting 1st ? as id and 2nd ? as id.
So

decode(5454,null,id,5454);

[Tim Cooke]

Here is the syntax illustration from the Oracle Documentation for DECODE which I linked to before.

Given that your example has 4 parameters it represents the following
decode(expr, search, result, default)
So as an example, if I had a table called PEOPLE with a column NAME I could write:
select decode(NAME, 'Tim', 'Hurrah!', 'Boo!') from PEOPLE;
Which would result in a dataset that contains "Hurrah!" for all rows that contain "Tim" in the NAME field and "Boo!" for all other rows.

So, given your usage example
decode(5454,null,id,5454);
You have your ID in the first parameter which should contain the column name. I'm guessing it's not working too well?