9 February

i). Machine. Config

ii). Web.Config (For desktops app.Config)

Common paints for confn files:

• These are simple text files & can be edited using any simple text editor.


• These are xml formatted (case sensitive) & any xml programs can use these files or they can be directly edited because xml is human readable.


• * They are automatically cached on memory for faster retrieval of settings (Cache memory àprogrammed memory area).


• * Processed in hierarchical manner which means every configuration file inherits its parent configuration file settings. The root for all these files is Machine.Config.


• Also called as configuration inheritance apart from this configuration is also hierarchical as xml is hierarchical.

Machine.Config points:

• It is called per-server basis file. Only one machine.config is allowed for one runtime/server.


• Located .NET framework folder not on our project & all settings are common to all websites running in that system. * 4 MB (default)(more than 4.0 go to machine.config – one file- change)


• Most of the settings are maintained by administrator but not by application developers.


• here we find all website settings(default) i.e., namespaces, services of support, net support, compileation settings, deploy settings, db settings ......

Web.Config points:

• It is called as application Configuration file.


• **** It is optional today also to have web.config in our application located in root & can be created sub folders also. We can create multiple web.config’s on our site maximum is how many folders we have in our project.


• we can perform the following functionalities in web.config file:

1.  Maintain connection strings


2. Custom errors


3. Security


4. Debugging


5. Tracing

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The Cursor Process has the following steps involved in it: (exception handling in sp)

• Declare a Cursor


• Open a Cursor


• Fetch data from the Cursor


• Close the Cursor


• De-allocate the Cursor

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“When a client, makes a request for an aspx page, it will be processed at server & all the result produced is concatenated as a single string along with some hash values in it.

These concatenated values are converted into base 64 format***. These base 64 values are stored in one or more hidden fields*** by server sent to client along with other from contents.

User adds/modifies the content & resubmits the form to server. Server first reads the hidden field values so that it retains the last given values (act as stateful) &responds the same process with new repeated as long as user is working with current page....”

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What is the scope of application variable?

1. Accessible to all users of application, irrespective of the user who created it.


2. The common memory area which is created in the webserver, which is common for all the users is k.led as App. Memory.


3. Storing the data in this app.memory is k.ed App. state in State mngt. sys      


4. .: The values stord by the webuser in the app memory, can be accessed by the other users also.                  


5. The App State can store obj data types.


6. App.State have to be used to store the Data which will be common for all the users of website.

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All session variables are accessible to current user only.

Session variable are also of type object which means they can store any type of data (Load on server should be considered).

Session data will be stored @ server only & only session id travels. This data will be available as long as session is preserved by server. Sessions are normally ended based on timeout***.

In ASP.NET by default 20 min’s it the timeout (idle timeout) using configuration settings as well as programmatically with session object we can change this default time.

A session can be ended programmatically also. Session object has a method called Abandon () which kills the current session.

<system.web>

<SessionState timeout=”10”></SessionState>

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Non.Persistent Cookies: These Cookies will be created in the browser's process area. They r not mentioned with Time duration. These Cookies will be destroyed when the app is closed

Persistent Cookies: The Cookies which are created & exists for a given time duration., is k.ld as the Persistent Cookie. They are created in the Client machine

Query string:                                                                                                                                                               Query string is Client side st.mngt sys. It can hold only strings. The Query string Memory will destroyed, when the app is closed.                                                                                                                                                The values Stored in Query string can be accessed from any page through out the app. In general Query string is used 2 carry small values from one to another page.

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1. Caching is the process of storing the page or objects in the cache memory of browse, proxy servers or webserver.      


2. in general, caching is used to improve the performance i.e., the page or object that is cached will be accessed from the cache memory tor the next request with out fetching it from the db server.


3. caching can be done at client side as well as server side.

These are 3 types of caching:

client side caching:

• output page caching (or) entire page caching


• fragment caching (or) partial page caching

server side caching:

• data caching (or) object caching.

using system.web.caching;

//create{                                                                                                                                                                                                            CacheDependency cd = new Cache Dependency(Server.MapPath("XMLfile.xml"), Cache.Insert("key1",ds.Tables[0]),cd,DateTime.Now.AddMinutes(10),Cache.NoSlidingExpression);              }

//get{                                                                                                                                                                                         gv1.DataSource = (DataTable)Cache.Get("key1");                                                                                                                      gv1.DataBind();                                                                                                                                                                                             }

1. Obj caching or data caching is server side State Management Sys.


2. we can create this kind of caching in 2 cryterious

• cache dependency: By using this, cache memory will be destroyed if the dependent file is modified.


• cache expiration: By using this parameter, cache mem. will be destroyed with in a given time after the creation.

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Primary Key:
Primary Key enforces uniqueness of the column on which they are defined.
Primary Key creates a clustered index on the column.
Primary Key does not allow Nulls.

CREATE TABLE EMP (eID INT NOT NULL PRIMARY KEY,
eName VARCHAR(100) NOT NULL)

Alter table with Primary Key:
ALTER TABLE EMP
ADD CONSTRAINT pk_eID PRIMARY KEY (eID)

Unique Key:
Unique Key enforces uniqueness of the column on which they are defined.
Unique Key creates a non-clustered index on the column.
Unique Key allows only one NULL Value.

Alter table to add unique constraint to column:
ALTER TABLE EMP ADD CONSTRAINT UK_empName UNIQUE(empName)

SQL SERVER – Introduction to JOINs – Basic of JOINs

INNER JOIN

This join returns rows when there is at least one match in both the tables.

OUTER JOIN

There are three different Outer Join methods.

LEFT OUTER JOIN
This join returns all the rows from the left table in conjunction with the matching rows from the right table. If there are no columns matching in the right table, it returns NULL values.


RIGHT OUTER JOIN
This join returns all the rows from the right table in conjunction with the matching rows from the left table. If there are no columns matching in the left table, it returns NULL values.


FULL OUTER JOIN
This join combines left outer join and right outer join. It returns row from either table when the conditions are met and returns null value when there is no match.

CROSS JOIN

This join is a Cartesian join that does not necessitate any condition to join. The resultset contains records that are multiplication of record number from both the tables.

Additional Notes related to JOIN:

The following are three classic examples to display where Outer Join is useful. You will notice several instances where developers write query as given below.

SELECT t1.*
FROM Table1 t1
WHERE t1.ID NOT IN (SELECT t2.ID FROM Table2 t2)
GO

The query demonstrated above can be easily replaced by Outer Join. Indeed, replacing it by Outer Join is the best practice. The query that gives same result as above is displayed here using Outer Join and WHERE clause in join.

/* LEFT JOIN - WHERE NULL */
SELECT t1.*,t2.*
FROM Table1 t1
LEFT JOIN Table2 t2 ON t1.ID = t2.ID
WHERE t2.ID IS NULL



The above example can also be created using Right Outer Join.



NOT INNER JOIN
Remember, the term Not Inner Join does not exist in database terminology. However, when full Outer Join is used along with WHERE condition, as explained in the above two examples, it will give you exclusive result to Inner Join. This join will give all the results that were not present in Inner Join.



You can download the complete SQL Script here, but for the sake of complicity I am including the same script here.

USE AdventureWorks
GO
CREATE TABLE table1
(ID INT, Value VARCHAR(10))
INSERT INTO Table1 (ID, Value)
SELECT 1,'First'
UNION ALL
SELECT 2,'Second'
UNION ALL
SELECT 3,'Third'
UNION ALL
SELECT 4,'Fourth'
UNION ALL
SELECT 5,'Fifth'
GO
CREATE TABLE table2
(ID INT, Value VARCHAR(10))
INSERT INTO Table2 (ID, Value)
SELECT 1,'First'
UNION ALL
SELECT 2,'Second'
UNION ALL
SELECT 3,'Third'
UNION ALL
SELECT 6,'Sixth'
UNION ALL
SELECT 7,'Seventh'
UNION ALL
SELECT 8,'Eighth'
GO
SELECT *
FROM Table1
SELECT *
FROM Table2
GO
USE AdventureWorks
GO
/* INNER JOIN */
SELECT t1.*,t2.*
FROM Table1 t1
INNER JOIN Table2 t2 ON t1.ID = t2.ID
GO
/* LEFT JOIN */
SELECT t1.*,t2.*
FROM Table1 t1
LEFT JOIN Table2 t2 ON t1.ID = t2.ID
GO
/* RIGHT JOIN */
SELECT t1.*,t2.*
FROM Table1 t1
RIGHT JOIN Table2 t2 ON t1.ID = t2.ID
GO
/* OUTER JOIN */
SELECT t1.*,t2.*
FROM Table1 t1
FULL OUTER JOIN Table2 t2 ON t1.ID = t2.ID
GO
/* LEFT JOIN - WHERE NULL */
SELECT t1.*,t2.*
FROM Table1 t1
LEFT JOIN Table2 t2 ON t1.ID = t2.ID
WHERE t2.ID IS NULL
GO
/* RIGHT JOIN - WHERE NULL */
SELECT t1.*,t2.*
FROM Table1 t1
RIGHT JOIN Table2 t2 ON t1.ID = t2.ID
WHERE t1.ID IS NULL
GO
/* OUTER JOIN - WHERE NULL */
SELECT t1.*,t2.*
FROM Table1 t1
FULL OUTER JOIN Table2 t2 ON t1.ID = t2.ID
WHERE t1.ID IS NULL OR t2.ID IS NULL
GO
/* CROSS JOIN */
SELECT t1.*,t2.*
FROM Table1 t1
CROSS JOIN Table2 t2
GO
DROP TABLE table1
DROP TABLE table2
GO