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SQL - View

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SQL
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This presentation will cover:
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A Brief History of DBMS
пЃ¬ View
in database
пЃ¬ MySQL installation
SQL – DBMS History
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DBMS History
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The IBM’s System/R was not the first DBMS. The
first to market was Relational Software's product
named Oracle
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The second was Relational Technology's Ingres.
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IBM then released improved products in 1982
named SQL/DS and DB2. Oracle and DB2 in nth
generation forms while the Ingres technology was
bought by Computer Associates.
SQL - Standards
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SQL is a open language without corporate ownership.
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The ANSI-SQL (American National Standards Institute)
group has published three standards over the years:
SQL89 (SQL1)
SQL92 (SQL2)
SQL99 (SQL3)
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The majority of the language has not changed through
these updates.
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The SQL standard from ANSI is considered the "pure"
SQL and called ANSI-SQL.
SQL – Enhanced features
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Every DBMS vendor wants their products to be different.
So most products offers extra features, these additions
are generally not compatible with competitor's SQL
products.
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It is always safest to stick with pure SQL
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The enhancements are not all bad because these
extensions are very useful.
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For example, most DBMS sold today have an
automatic way to assign a serial number feature
since serial numbering is so common. However, the
method of implementation is not uniform.
What is a View?
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In SQL, a VIEW is a virtual relation based on the
result-set of a SELECT statement.
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A view contains rows and columns, just like a real
table. The fields in a view are fields from one or more
real tables in the database. In some cases, we can
modify a view and present the data as if the data
were coming from a single table.
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Syntax:
CREATE VIEW view_name AS
SELECT column_name(s)
FROM table_name
WHERE condition
SQL – Relations, Tables & Views
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1.
When we say Relation, it could be a Table or a View.
There are three kind of relations:
Stored relations
tables
We sometimes use the term “base relation” or “base
table”
2. Virtual relations
views
3. Temporary results
SQL – Create View
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Example: Create a view with title and year and made by
Paramount studio.
Movie (title, year, length, inColor, studioName,
producerC#)
CREATE VIEW ParamountMovie AS
SELECT title,year
FROM Movie
WHERE studioName = �Paramount’;
SQL – Querying View
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A view could be used from inside a query, a stored
procedure, or from inside another view. By adding
functions, joins, etc., to a view, it allows us to present
exactly the data we want to the user.
View
SELECT title
FROM ParamountMovie
WHERE year = �1979’;
Have same result as
Table
SELECT title
FROM Movie
WHERE studioName = �Paramount’ AND year =
�1979’;
SQL - Querying View con’t
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Query involving both view and table
SELECT DISTINCT starName
View
FROM ParamountMovie, StarsIn
Table
WHERE title = movieTitle AND year =
movieYear;
SQL - Querying View example
Movie (title, year, length, inColor, studioName, producerC#)
MovieExec (name, address, cert#, netWorth)
CREATE VIEW MovieProd AS
SELECT title, name
FROM Movie, MovieExec
WHERE producerC# = cert#;
SELECT name
FROM MovieProd
WHERE title = �Gone With the Wind’;
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Same result as query from tables
SELECT name
FROM Movie, MovieExec
WHERE producerC# = cert# AND title = �The War Of the World’;
SQL - Renaming Attributes in View
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Sometime, we might want to distinguish
attributes by giving the different name.
CREATE VIEW MovieProd (movieTitle, prodName) AS
SELECT title, name
FROM Movie, MovieExec
WHERE producerC# = cert#;
SQL - Modifying View
When we modify a view, we actually modify a table
through a view. Many views are not updateable. Here
are rules have been defined in SQL for updateable
views:
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selecting (SELECT not SELECT DISTINCT) some
attributes from one relation R (which may itself be an
updateable view)
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The WHERE clause must not involve R in a
subquery.
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The list in the SELECT clause must include enough
attributes that will allow us to insert tuples into the
view as well as table. All other attributes will be
filled out with NULL or the proper default values.
SQL – Modifying View (INSERT)
INSERT INTO ParamountMovie
VALUES (�Star Trek’, 1979);
To make the view ParamountMovie updateable, we need to add
attribute studioName to it’s SELECT clause because it makes
more sense if the studioName is Paramount instead of NULL.
CREATE VIEW ParamountMovie AS
SELECT studioName, title, year
FROM Movie
WHERE studioName = �Paramount’;
Then
INSERT INTO ParamountMovie
VALUES (�Paramount’, �Star Trek’, 1979);
Title
year length
�Star Trek’ 1979
0
inColor
NULL
studioName
�Paramount’
producerC#
NULL
SQL - Modifying View (DELETE)
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Suppose we wish to delete all movies with
“Trek” in their title from the updateable view
ParamountMovie.
DELETE FROM ParamountMovie
WHERE title LIKE �%Trek%’;
It is turned into the base table delete
DELETE FROM Movie
WHERE title LIKE �%Trek%’ AND studioName =
�Paramount’;
SQL - Modifying View (UPDATE)
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UPDATE from an updateable view
UPDATE ParamountMovie
SET year = 1979
WHERE title = �Star Trek the Movie’;
It is turned into the base table update
UPDATE Movie
SET year = 1979
WHERE title = �Star Trek the Movie’ AND studioName
= �Paramount’;
SQL – View (DROP)
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DROP view: All views can be dropped, whether or not
the view is updateable.
DROP VIEW ParamountMovie;
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DROP VIEW does not affect any tuples of the
underlying relation (table) Movie.
However, DROP TABLE will delete the table and also
make the view ParamountMovie unusable.
DROP TABLE Movie
SQL - Download MySQL
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Go to http://dev.mysql.com/downloads/ and
download:
MySQL (Windows User / version 4.1.10a, 5.0.2alpha has bug that keep shutting down the
service)
пѓ� MySQL Administrator
пѓ� MySQL Query Browser
SQL – Install MySQL
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During the installation –
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you can <“Skip Sing-Up”> to fast installation
Will run Configuration Wizard right after installation
automatically
If the service won’t start, press <cancel>, then run
Configuration Wizard manually again
Run MySQL Server Instance Config Wizard from
windows menu –
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use default setting unless you know what you are doing
Modify Security Setting (option: you can start service without
doing this)
Execute
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If there is an error, try press <back> to go back, then press <next>
to <execute> again
TCP / IP Networking –
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Try different port number if you are using networking.
SQL - MySQL Administrator
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MySQL Administrator come with MySQL
System Tray Monitor allow you to configure
your server
 Run MySQL Administrator –
 For the first time, you may not have “Stored
connection,” you can <Add new Connection>
and give the Connection name.
 Server Host: type “localhost” If you don’t use
networking
SQL - MySQL Query Browser
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Run MySQL Query Browser
пЃ¬ Give a name for the Default Schema
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Schema means Database instance
You can type command line into the top box
or right Click on schemata to create new
table
SQL - Bibliography
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First Course In Database Systems, Jeffery D.
Ullman and Jennifer Widom,1997 Prentice Hall,
Inc.
пЃ¬ http://mysql.com
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