Aggregate Functions:



 They are used to compute a single value from a set  of attribute values of a column:
   count :
            how many rows(tuples) are stored in the relation EMP
select count(*) from EMP;
            how many different job title  are stored in the relation EMP
select count(distinct job) from EMP;
max & min:
           select min(SAL),max(SAL) from EMP
           select max(SAL)- min(SAL)  from EMP
sum:
         select sum(SAL) from EMP
avg:





No comments:

PL/SQL



Structure of PL/SQL:
     Declare
              <Constants>
               <Variables>
               <Cursors>
                <User defined exceptions>
Begin
         <PL/SQL Statements>
          exception
               <exception handling>
End

Know in PL/SQL:
About
1.Exception handling
2.Procedures
3.Functions
4.assertions
5.Triggers

No comments:

Tags



<abbr> Tag

The <abbr> tag is supported in all major browsers.
<abbr title="World Health Organization">WHO</abbr>
Note: The <abbr> tag is not supported in IE 6 or earlier versions.
Tip: The global title attribute can be used in the <abbr> tag to show the full version of the abbreviation/acronym when you mouse over the <abbr> element.
<acronym>  Tag
<acronym title="as soon as possible">ASAP</acronym>

<bdo> Tag

<bdo dir="rtl">
This text will go right-to-left.
</bdo>

<caption> Tag

<table border="1">
  <caption>Monthly savings</caption>
  <tr>
    <th>Month</th>
    <th>Savings</th>
  </tr>
  <tr>
    <td>January</td>
    <td>$100</td>
  </tr>
</table>
The <caption> tag defines a table caption.

<col> Tag

table border="1">
  <colgroup>
    <col span="2" style="background-color:red">
    <col style="background-color:yellow">
  </colgroup>
  <tr>
    <th>ISBN</th>
    <th>Title</th>
    <th>Price</th>
  </tr>
  <tr>
    <td>3476896</td>
    <td>My first HTML</td>
    <td>$53</td>
  </tr>
</table

<del> Tag

<p>My favorite color is <del>blue</del> <ins>red</ins>!</p>

<fieldset> Tag

<!DOCTYPE html>
<html>
<body>
<form>
 <fieldset>
  <legend>Personalia:</legend>
  Name: <input type="text"><br>
  Email: <input type="text"><br>
  Date of birth: <input type="text">
 </fieldset>
</form>
</body>
</html>

<hr> Tag

<!DOCTYPE html>
<html>
<body>

<h1>HTML</h1>
<p>HTML is a language for describing web pages.</p>

<hr>

<h1>CSS</h1>
<p>CSS defines how to display HTML elements.</p>

</body>
</html>

<mark> Tag

<!DOCTYPE html>
<html>
<body>

<p>Do not forget to buy <mark>milk</mark> today.</p>

</body>
</html>

<meter> Tag

<!DOCTYPE html>
<html>
<body>

<p>Display a gauge:</p>
<meter value="2" min="0" max="10">2 out of 10</meter><br>
<meter value="0.6">60%</meter>

<p><b>Note:</b> The &lt;meter&gt; tag is not supported in IE and Safari.</p>

</body>
</html>

<nav> Tag

<!DOCTYPE html>
<html>
<body>

<nav>
<a href="/html/">HTML</a> |
<a href="/css/">CSS</a> |
<a href="/js/">JavaScript</a> |
<a href="/jquery/">jQuery</a>
</nav>

</body>
</html>

<optgroup> Tag

<!DOCTYPE html>
<html>
<body>

<select>
  <optgroup label="Swedish Cars">
    <option value="volvo">Volvo</option>
    <option value="saab">Saab</option>
  </optgroup>
  <optgroup label="German Cars">
    <option value="mercedes">Mercedes</option>
    <option value="audi">Audi</option>
  </optgroup>
</select>

</body>
</html>

<param> Tag

<!DOCTYPE html>
<html>
<body>

<p><b>Note:</b> IE does not support .wav files. Try to rename the file to "horse.mp3" to test the example in IE.</p>

<object data="horse.wav">
<param name="autoplay" value="true">
</object>

</body>
</html>

<pre> Tag

<!DOCTYPE html>
<html>
<body>

<p><b>Note:</b> IE does not support .wav files. Try to rename the file to "horse.mp3" to test the example in IE.</p>

<object data="horse.wav">
<param name="autoplay" value="true">
</object>

</body>
</html>

<progress> Tag

<!DOCTYPE html>
<html>
<body>

Downloading progress:
<progress value="50" max="100">
</progress>

<p><b>Note:</b> The &lt;progress&gt; tag is not supported in IE and Safari.</p>

</body>
</html>

<s> Tag

<!DOCTYPE html>
<html>
<body>

<p><s>My car is blue.</s></p>
<p>My new car is silver.</p>

</body>
</html>

<strike>

<!DOCTYPE html>
<html>
<body>

<p>Version 2.0 is <strike>not yet available!</strike> now available!</p>

</body>
</html>

<sub> and <sup> Tags

<!DOCTYPE html>
<html>
<body>

<p>This text contains <sub>subscript</sub> text.</p>
<p>This text contains <sup>superscript</sup> text.</p>

</body>
</html>



No comments:

OSI Model

Open System Interconnection Model:
Physical Layer:
it performs all the functions related for establishing a physical home of communication
like hardware specification,topology,encoding n signaling etc.

Data Link Layer:
it provides the reliable transmission of a packet using physical layer services.Means it links the data to physical layer.
it is also dived into two parts Medium acces layer and Logical Link layer

Network Layer:
It provides the way of transmission of packets(routing) n also congestion control n internetworking.

Transport Layer:
it performs the transmission of packets like using Multiplexing/demultiplexing,fregmentation,error control,flow control etc.

Session Layer:
It is responsible for all the authorization security by creating sessions.

Presentation Layer:
It tells us that in which syntax n semantics  the informations should be transmitted n also include compression,encryption.

Application Layer:
Application layer refers to Application Protocol.The choice of which specific protocol n thier associated functions r to be used at the application lavel is up to the individual user HTTP,FTP etc.
No comments:

Codes

No comments:
Subscribe to: Posts (Atom)

Counters