[Student] Ado.net and SQL

7/30/2019 [Student] Ado.net and SQL

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ADO.NET AND

STRUCTURED QUERY

LANGUAGE (SQL)Database Terminology, ADO.NET, Connecting toDatabase, SQL Statements


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Database

Relational Database

Entity

Table

AttributeColumn

Keys

Review: DatabaseFundamentals


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Databases

Database

A database is a collection of related data which is

organized to meet user needs

Relational database

database that stores information in tables

Each column represents a field

Each row represents a record

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Entities

An enti ty is a class of objects, such as people,

products, or services, about which we collect

data. For example,

Students at the university.

Employees at a business.

Sales transactions in a retail business.

Inventory of parts in a warehouse.

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Tables

Table

a group of related records

a physical implementation of an entity in a DBMS

Relational database contains one or more

tables

Primary key

a field that uniquely identifies each record in a

table

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Attributes and Columns

An attr ibute is a characteristic of an entity

Examples of attributes

Names, addresses, phone numbers of people. Titles, salaries, job descriptions of employees.

Time, date, customer id, sales person id in a sales

transaction.

Part number, Cost, In-stock-quantity of inventoryof parts.

A co lumn , orf ield, is a physical

implementation of an attribute.

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Keys

Keys are the attributes that are used to

uniquely identify each instance of an entity, i.e.

each row in a table

The uniqueness can naturally occur like Social

Security numbers or can be created by the

database management system. For example,

Student IdEmployee number

Part number

Social Security Number

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What is ADO.NET

ADO.NET Objects

Data Providers

ADO.NET


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What is ADO.NET?

It is a Microsoft Technology.

Stands forActiveX Data Objects

It is a programming language interface toaccess data in a database.

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ADO.NET

To connect an application to a database,

ASP.NET uses ADO.NET

With ADO.NET, the connection between an

application and a database is a temporary one.

ADO.NET objects and provider are needed to

access a database from a ASP.NET

application:Connection

Command

DataReader


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.NET Framework Data Providers

A .NET Framework data provider is used for connecting

to a database, executing commands, and retrieving

results.

.NET Frameworkdata provider Description

SQL Server Provides data access for Microsoft SQL Server. Uses

the System.Data.SqlClient namespace.

OLE DB For data sources exposed by using OLE DB. Uses

the System.Data.OleDb namespace.

ODBC For data sources exposed by using ODBC. Uses

the System.Data.Odbc namespace.

Oracle For Oracle data sources. The .NET Framework Data Provider

for Oracle supports Oracle client software version 8.1.7 and

later, and uses the System.Data.OracleClient namespace.

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Connection Object (1/3)

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 otherparameters 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. In ASP.NET, we are going to store the connection string

needed by the connection object in a web.config file.

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Sample web.config (using OleDb provider):

Using SqlClient provider

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How to use the connection string inside the web.config

file:

Include using System.Configuration

Using OleDB connection object

Using SqlClient connection object

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string conn =

ConfigurationManager.ConnectionStrings[MyConnectionString"].ConnectionString;

OleDbConnection myCon = new OleDbConnection(conn);

string conn =ConfigurationManager.ConnectionStrings[ConnectionString"].ConnectionString;

SqlConnection myCon = new SqlConnection(conn);


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Command Object (1/2)

The process of interacting with a database means that

you must specify the actions you want to occur.

A command object sends SQL statements to the

database. A command object uses a connection object tofigure out which database to communicate with.

Sample code:

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SqlCommand cmd;

cmd= new SqlCommand(sql, conObject);cmd.ExecuteNonQuery();


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Command Object (2/2)

Some Command object methods:

cmd.ExecuteReader() Returns one or more

table row(s) for select statement

cmd.ExecuteNonQuery() Used for executing

stored procedure or insert/update/delete

statements

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DataReader Object

Reads a forward-only, read-only stream of data

from a data source.

Sample code:

SqlCommand cmd;cmd= new SqlCommand(SELECT * FROM Students, myCon);SqlDataReader dr= cmd.ExecuteReader();while (dr.Read()){

string name = dr.GetString(0);string year = dr.GetString(1);string course = dr.GetString(2);lstIOutput.Items.Add(Name = + name);lstIOutput.Items.Add(Year = + year);lstIOutput.Items.Add(Course = + course);

}


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DataAdapter Object

Populates a DataSet/ DataTable and resolves

updates with the data source.

DataSet

contains a collection of zero or more tables

represented by DataTable objects

DataTable

represents a single table of memory-resident data

Defined in the System.Data namespace


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Brief Introduction to SQL

Types of SQL Statements

Structured Query Language (SQL)


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SQL

SQL (Structured Query Language): a set of commands

to access and manipulate the data stored in many

database management systems

SQL commands perform database tasks such as storing,retrieving, updating, deleting, and sorting.

In SQL, we will write queries.

A query is a formalized instruction to a database toeither return a set of records or perform a specific actionon a set of records as specified in the query


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SQL Commands

SELECT

UPDATE

INSERT INTO DELETE

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SELECT Statement

Selects/extracts data from one or more database

tables.

Syntax:

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SELECT columnName1, columnName2,FROM tableName[WHERE condition]

[ORDER BY columnName ASC|DESC]


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Table Name: Student

To select all Lastname from the above table, we will use this

SQL SELECT statement:

Result:

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StudentID Lastname Course

200601137 Sabale BCS

200600459 Que HRM

200601020 Lumandas JOU201001423 Luis BCS

SELECT Statement Example 1


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Table Name: Student

To select all records ofBCS studentsfrom the above table,

we will use this SQL SELECT statement:

Result:

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200600459 Que HRM




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Table Name: Student

To display all Course in ascending order from the above

table, we will use this SQL SELECT statement:

Result:

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200600459 Que HRM




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Table Name: Student

What is the result of the SQL statement below?

SELECT Course FROM Student WHERE Lastname IN (Cu,

Luis, Que)

Result:

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200600459 Que HRM




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Table Name: Student

If we want to know the lastname and course of all students

aged 16 to 20, the SQL statement is:

Result:

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StudentID Lastname Course Age

200601137 Sabale BCS 17

200600459 Que HRM 19

200601020 Lumandas JOU 20201001423 Luis BCS 16



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UPDATE Statement

Updates data in a database table.

Syntax:

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UPDATE tableNameSET colName1 = newValue, colName2 = newValue,[WHERE condition]


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Table Name: Student

To change the course of all students to BCS, we will use this

SQL UPDATE statement:

Result:

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200600459 Que HRM


UPDATE Statement Example 1


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Table Name: Student

To change the lastname to Sarnoand course to MSCS of

student id 20061137, the SQL statement is:

Result:

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200600459 Que HRM




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Table Name: Student

What is the result of the following command?

UPDATE Student SET Lastname= Sarno WHERE StudentID

= 200601137 AND Course = JOU

Result:

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200600459 Que HRM




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Table Name: Student

What is the result of the following command?

UPDATE Student SET Lastname= Masdal WHERE

StudentID = 200600459 OR Course = JOU

Result:

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200600459 Que HRM




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INSERT INTO Statement

Inserts new data into a database table

Syntax:

Or:

You are allowed to omit the list of column names in theINSERT INTO clause, if you enter values for each of the table

columns.

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INSERT INTO

tableName (column1, column2, column3,...)VALUES(value1, value2, value3,...)

INSERT INTO tableName

VALUES (value1, value2, value3,...)


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Table Name: Student

To insert this data (201001520, Rosario, MID) to the table:

Result:

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200600459 Que HRM

200601020 Lumandas JOU

INSERT INTO Statement Example 1


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Table Name: Student

To insert this data (201001234) to the table:

Result:

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200600459 Que HRM


INSERT INTO Statement Example 2


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DELETE Statement

Delete records in a table

Syntax:

Or, to delete all records in a table:

Note: Be very careful when deleting records. You cannot

undo this statement.

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DELETE FROM tableNameWHERE someColumn=someValue

DELETE FROM tableName


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Table Name: Student

To delete the student Lumandas with course JOU in the

table:

Result:

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200600459 Que HRM


201001423 Luis BCS

DELETE Statement Example 1


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Table Name: Student

To delete all records in table Student:

Result:

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200600459 Que HRM


201001423 Luis BCS

DELETE Statement Example 2

St i S l ti R d f


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1. Create a DataAdapter.

2. Create a DataTable.

3. Fill/ populate the table using the DataAdapter.

4. Bind to a data-bound control.

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Steps in Selecting Records from a

Database

SqlDataAdapter da;

da = new SqlDataAdapter("SELECT * FROM tableName", con);

DataTable dt = new DataTable();

da.Fill(dt);

sqlDataSource1.DataSource = dt;

St i I ti U d ti


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1. Create an ADO.NET connection to a database.

2. Create a String the represents the SQL command.

3. Create a Command object.

4. Open the connection.

5. Execute the SQL statement.

6. Close the connection.

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Steps in Inserting, Updating, or

Deleting Records in a Database

SqlConnection con = new SqlConnection(connectionString);

con.Open();

SqlCommand com = new SqlCommand(sql, con);

com.ExecuteNonQuery();

con.Close();

String sql = [INSERT INTO] or [UPDATE] or [DELETE] command


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Reference

Introduction to C# Programming with

Microsoft.NET

http://msdn.microsoft.com

http://csharp-station.com/Tutorial/AdoDotNet/Lesson01

Documents

[Student] Ado.net and SQL