طريقة كتابة اوامر( Select ) للمبتدئين

[abu_fahad]

<span style='font-family:tahoma'></span>

</div><div align="center">بسم الله الرحمن الرحيم

Displaying Table Structure:

In SQL*Plus, you can display the structure of a table using the DESCRIBE command. The result of the command is to see the column names, Datatypes, and whether a column must contain data.
*********************
DESC[RIBE]  tablename
********************

Where:	tablename		is the name of any existing table, view, or synonym accessible to the user.

Example:

Display information about the structure of the S_DEPT table.

#####################
SQL> DESCRIBE  s_dept
#####################


NAME		NULL?		Type
---------		---------		-------
ID			NOT NULL		NUMBER (7)
NAME		NOT NULL		VARCHAR2 (25)
REGION_ID				NUMER (7)
###########################



Where:	Null?		Indicates that a column must contain data.

	Type		displays the datatype for a column.
&&&&&&&&&&&&&&&&&&&&&&&&
Datatype                       Description
=======================================
NUMBER (p,s)````          Description
***************************
VARCHAR2(s)                Number value having a maximum number of digits p , and the number of digits to the right of the decimal point s .
**********************************
DATE                    Variable length character value of maximum size s .
*************************************
CHAR(s)        Fixed length character value of size s.
================================



The Basic Query Block:

A SELECT statement retrieves information from the database, implementing all algebraic operators .

Syntax
¬+++++++++++++++++++++++
SELECT		(DISTINCT)	{* , column [alias] , …. }
FROM		table ;
+++++++++++++++++++++++

Where :	SELECT		is a list of at least one column .
	DISTINCT suppresses duplicates .
	*			select all columns .
	column		selects the named column .
	alias gives selected columns a different heading
	FROM table specifies the table containing the columns.

Selecting All Columns and Rows
The asterisk (*) selects all columns from the table .
Example 

List all columns and all rows from the S_DEPT table .
&&&&&&&&&&&&&&&&&&&&&&
SQL> SELECT   *
    2    FROM       s_dept;
##################################


ID	NAME				REGION_ID
----    ---------                                    ------------------
10	Finance				                 1
31	Sales						       1
32	Sales						       2
33	Sales						       3
34	Sales						       4
35	Sales						       5
41	Operations					       1
42	Operations					       2
43	Operations					       3
44	Operations					       4
45	Operations					       5
50	Administration				       1
12 Rows selected .
###################################################


Selecting Specific Columns: 

You restrict the query to display only certain columns by specifying the column names , separated by commas , in the SELECT clause .

Example: 

Display all department numbers, employee last names, and manager numbers in the S_EMP table .
######################
SQL> SELECT	dept_id, last_name, manager_id
    2	 FROM	s_emp;
**********************

DEPT_ID	LAST_NAME		MANAGER_ID
-------------	-------------------		---------------------
50	Velasquez
41	Ngao						 1
31	Nagayama					 1
10	Quick-to-see				 1
50	Ropeburn					 1
41	Urguhart					 2
42	Menchu					 2
43	Biri						 2
44	Catchpole					 2
…

25 rows selected   	 
==========================================

المعذرة بعض الأرقام بالعربي وبعض الفواصل مقلوبة مادري ليش
(( والدروس القادمة افضل ان شاء الله))
وشكر الأخوان الأفاضل القائمين على هذا النتدى
(( محبكم ابوفهد [email protected] ))

[khaledmega]

السلام عليكم
اولا مجهود تستحق عليه الشكر ولكن انت فى منتدي عربي فحاول ان توضح افكارك وشرحك مدعما باللغة العربي .
الامر الثاني اكتب ما تشاء من شرح ولكن على Text Document وارفقه فى المرفقات وستجد الاوامر مكتوبة بشكل سليم ان شاء الله وستجد من يرد عليك فى كتاباتك
وشكرا
ميجا

[elsmahy83]

شكرا بس مفهمتش اي حاجة
لانك كاتب كلة انجليزي
لوانا عاوز اتعلم بالانجليزي كان ممكن اشترك في منتدي انجليزي
شكرا ليك كمان مرة

[mk3bmw]

موضوع رائع ولكن يحتاج بعض الترتيب