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Mata kuliah : M0874 – Programming II
Tahun
: 2010
Database, SQL, and ADO .NET- Part 1
Session 11
Outline Materi
•Introduction
•Relational Database Model
•Structured Query Language
•ADO .NET Object Model
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Introduction
•A database is an integrated collection of data.
•A database management system (DBMS) provides
mechanisms for storing and organizing data in a manner that
is consistent with the database’s format.
•Database management systems enable programmers to
access and store data without worrying about the internal
representation of databases.
•Today’s most popular database systems are relational
databases.
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Introduction
•Almost universally, relational databases use a
language called Structured Query Language (SQL) to
perform queries and to manipulate data.
•A programming language connects to, and interacts
with, a relational database via an interface-software
that facilitates communication between a database
management system and a program.
•C# programmers communicate with databases and
manipulate their data through Microsoft ActiveX Data
ObjectsTM (ADO), ADO .NET.
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Relational Database Model
•The relational database model is a logical representation of
data that allows relationships among data to be considered
without concern for the physical structure of data.
Record/Row
number name
department
salary Location
23603
Jones
413
1100
New Jersey
24568
Kerwin
413
2000
New Jersey
34589
Larson
642
1800
Los Angeles
35761
Myers
611
1400
Orlando
78321
Neuman
n
413
9000
New Jersey
Primary key
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Field/Column
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Structured Query Language (SQL)
•Basic SELECT Query
SELECT * FROM tableName
(*) indicates that all columns from the tableName
table of the database should be selected.
Example:
SELECT * FROM Authors
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SQL Query Keywords
SQL Keyword
Description
SELECT
Selects (retrieves) fields from one or more tables
FROM
Specifies tables from which to get fields or delete records.
Required in every SELECT and DELETE statement.
WHERE
Specifies criteria that determine the rows to be retrieved.
INNER JOIN
Joins records from multiple tables to produce a single set of
records.
GROUP BY
Specifies criteria for grouping records.
ORDER BY
Specifies criteria for ordering records.
INSERT
Inserts data into a specified table.
UPDATE
Updates data in a specified table.
DELETE
Deletes data from a specified table.
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WHERE Clause
•In most cases, users search a database for records
that satisfy certain selection criteria.
•Only records that match the selection criteria are
selected.
SELECT fieldName1, fieldName2, … FROM tableName
WHERE criteria
•Example:
To select the name, salary, and location fields from table
Employee in which the salary is greater than 1800.
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WHERE Clause
SELECT name, salary, location
FROM Employee
WHERE salary > 1800
number name
department
salary Location
23603
Jones
413
1100
New Jersey
24568
Kerwin
413
2000
New Jersey
34589
Larson
642
1800
Los Angeles
35761
Myers
611
1400
Orlando
78321
Neuman
n
413
9000
New Jersey
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ORDER BY Clause
•The result of a query can be arranged in ascending or descending order using the
optional ORDER BY clause.
SELECT fieldName1, fieldName2,…FROM tableName ORDER BY field ASC
SELECT fieldName1, fieldName2,…FROM tableName ORDER BY field DESC
ASC specifies ascending order (lowest to highest)
DESC specifies descending order (highest to lowest)
Field specifies the field whose values determine the sorting order
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ORDER BY Clause
•Example:
SELECT name, salary, location
FROM Employee
ORDER BY name ASC
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Merging Data from Multiple Tables: INNER JOIN
•Database designers often split related data into
separate tables to ensure that a database does not
store data redundantly.
•Often, it is necessary for analysis purposes to merge
data from multiple tables into a single set of data.
•Referred to as joining the tables, this is accomplished
via an INNER JOIN operation in the SELECT query.
•An INNER JOIN merges records from two or more
tables by testing for matching values in a field that is
common to the tables.
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Merging Data from Multiple Tables: INNER JOIN
SELECT fieldName1, fieldName2, …
FROM table1
INNER JOIN table2
ON table1.fieldName = table2.fieldName
The ON part of the INNER JOIN clauses specifies
the fields from each table that are compared to
determine which records are joined.
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INSERT Statement
•The INSERT statement inserts a new record in a
table.
INSERT INTO tableName ( fieldName1, fieldName2, …,
fieldNameN )
VALUES ( value1, value2, …, valueN )
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ADO .NET Object Model
•ADO.NET is an object-oriented set of libraries that
allows you to interact with data sources.
•Commonly, the data source is a database, but it could
also be a text file, an Excel spreadsheet, or an XML file.
•The ADO .NET object model provides an API for
accessing database systems programmatically.
•ADO .NET was created for the .NET Framework and is
the next generation of ActiveX Data ObjectsTM (ADO).
•Namespace System.Data is the root namespace for the
ADO .NET API.
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ADO .NET Object Model
•ADO.NET allows us to interact with different types
of data sources and different types of databases.
•Different data sources expose different protocols,
we need a way to communicate with the right data
source using the right protocol.
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ADO .NET Object Model
•ADO.NET Data Providers are class libraries that allow a
common way to interact with specific data sources or
protocols. The library APIs have prefixes that indicate which
provider they support.
Provider Name
API
prefix
Data Source Description
ODBC Data Provider
Odbc
Data Sources with an ODBC interface. Normally older
data bases.
OleDb Data Provider
OleDb
Data Sources that expose an OleDb interface, i.e.
Access or Excel.
Oracle Data Provider
Oracle
For Oracle Databases.
SQL Data Provider
Sql
For interacting with Microsoft SQL Server.
Borland Data Provider
Bdp
Generic access to many databases such as Interbase,
SQL Server, IBM DB2, and Oracle.
ADO .NET Object Model
•ADO.NET includes many objects you can use to
work with data.
•The SqlConnection Object
•To interact with a database, you must have a connection to it. The
connection helps identify the database server, the database name,
user name, password, and other parameters that are required for
connecting to the data base. A connection object is used by
command objects so they will know which database to execute the
command on.
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ADO .NET Object Model
•The SqlCommand Object
•The process of interacting with a database means that you must specify the actions you want to
occur. This is done with a command object. You use a command object to send SQL statements to
the database.
•The SqlDataReader Object
•Many data operations require that you only get a stream of data for reading. The data reader object
allows you to obtain the results of a SELECT statement from a command object. For performance
reasons, the data returned from a data reader is a fast forward-only stream of data. This means that
you can only pull the data from the stream in a sequential manner. This is good for speed, but if you
need to manipulate data, then a DataSet is a better object to work with.
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ADO .NET Object Model
•The DataSet Object
•DataSet objects are in-memory representations of data. They
contain multiple Datatable objects, which contain columns and rows,
just like normal database tables.
•The SqlDataAdapter Object
•Sometimes the data you work with is primarily read-only and you
rarely need to make changes to the underlying data source. Some
situations also call for caching data in memory to minimize the
number of database calls for data that does not change. The data
adapter makes it easy for you to accomplish these things by helping
to manage data in a disconnected mode. The data adapter fills a
DataSet object when reading the data and writes in a single batch
when persisting changes back to the database.
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The SqlConnection Object
•A SqlConnection is an object, just like any other C#
object.
SqlConnection conn = new SqlConnection(
"Data Source=(local);Initial Catalog=Northwind;Integrated
Security=SSPI");
Connection String
Description
Parameter Name
Common parts of
a connection string
Data Source
Identifies the server. Could be local machine, machine
domain name, or IP Address.
Initial Catalog
Database name.
Integrated Security
Set to SSPI to make connection with user's Windows login
User ID
Name of user configured in SQL Server.
Password
Password matching SQL Server User ID.
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The SqlConnection Object
•The following shows a connection string, using the
User ID and Password parameters:
SqlConnection conn = new SqlConnection(
"Data Source=DatabaseServer;Initial Catalog=Northwind;User
ID=YourUserID;Pass=YourPass");
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Using a SqlConnection
•The purpose of creating a SqlConnection object is so you
can enable other ADO.NET code to work with a database.
•Other ADO.NET objects, such as a SqlCommand and a
SqlDataAdapter take a connection object as a parameter.
•The sequence of operations occurring in the lifetime of a
SqlConnection are as follows:
1.
2.
3.
4.
5.
Instantiate the SqlConnection.
Open the connection.
Pass the connection to other ADO.NET objects.
Perform database operations with the other ADO.NET objects.
Close the connection.
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References
•http://www.csharpstation.com/Tutorials/ADODotNet/Lesson01.aspx
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