다음을 통해 공유

ADO.NET 코드 예제

  • 아티클

이 항목에 나열된 코드에서는 다음과 같은 ADO.NET 기술을 사용하여 데이터베이스에서 데이터를 검색하는 방법을 보여 줍니다.

  • ADO.NET 데이터 공급자

    • .NET Framework Data Provider for SQL Server (System.Data.SqlClient)

    • .NET Framework Data Provider for OLE DB (System.Data.OleDb)

    • .NET Framework Data Provider for ODBC (System.Data.Odbc)

    • .NET Framework Data Provider for Oracle (System.Data.OracleClient)

  • ADO.NET Entity Framework:

    • LINQ to Entities

    • Typed ObjectQuery

    • EntityClient data provider (System.Data.EntityClient)

  • LINQ to SQL

ADO.NET 데이터 공급자 예제

다음에 나열된 코드에서는 ADO.NET 데이터 공급자를 사용하여 데이터베이스에서 데이터를 검색하는 방법을 보여 줍니다. 데이터는 DataReader에서 반환됩니다. 자세한 내용은 DataReader를 사용하여 데이터 검색(ADO.NET)을 참조하십시오.

SqlClient

이 예제 코드에서는 Microsoft SQL Server 7.0 이상 버전에서 Northwind 샘플 데이터베이스에 연결할 수 있다고 가정합니다. 이 코드에서는 Products 테이블에서 행을 선택하는 SqlCommand를 만들고 SqlParameter를 추가하여 UnitPrice가 지정한 매개 변수 값(이 경우 5)보다 큰 행만 반환되도록 제한합니다. 코드가 종료될 때 리소스가 닫히고 삭제되도록 SqlConnection이 using 블록 안에서 열립니다. 이 코드에서는 SqlDataReader를 사용하여 명령을 실행하고 결과를 콘솔 창에 표시합니다.

Option Explicit On
Option Strict On

Imports System
Imports System.Data
Imports System.Data.SqlClient

Public Class Program
    Public Shared Sub Main()

        Dim connectionString As String = _
            "Data Source=(local);Initial Catalog=Northwind;" _
            & "Integrated Security=true"

        ' Provide the query string with a parameter placeholder.
        Dim queryString As String = _
            "SELECT ProductID, UnitPrice, ProductName from dbo.Products " _
            & "WHERE UnitPrice > @pricePoint " _
            & "ORDER BY UnitPrice DESC;"

        ' Specify the parameter value.
        Dim paramValue As Integer = 5

        ' Create and open the connection in a using block. This
        ' ensures that all resources will be closed and disposed
        ' when the code exits.
        Using connection As New SqlConnection(connectionString)

            ' Create the Command and Parameter objects.
            Dim command As New SqlCommand(queryString, connection)
            command.Parameters.AddWithValue("@pricePoint", paramValue)

            ' Open the connection in a try/catch block. 
            ' Create and execute the DataReader, writing the result
            ' set to the console window.
            Try
                connection.Open()
                Dim dataReader As SqlDataReader = _
                 command.ExecuteReader()
                Do While dataReader.Read()
                    Console.WriteLine( _
                        vbTab & "{0}" & vbTab & "{1}" & vbTab & "{2}", _
                     dataReader(0), dataReader(1), dataReader(2))
                Loop
                dataReader.Close()

            Catch ex As Exception
                Console.WriteLine(ex.Message)
            End Try
            Console.ReadLine()
        End Using
    End Sub
End Class

using System;
using System.Data;
using System.Data.SqlClient;

class Program
{
    static void Main()
    {
        string connectionString =
            "Data Source=(local);Initial Catalog=Northwind;"
            + "Integrated Security=true";

        // Provide the query string with a parameter placeholder.
        string queryString =
            "SELECT ProductID, UnitPrice, ProductName from dbo.products "
                + "WHERE UnitPrice > @pricePoint "
                + "ORDER BY UnitPrice DESC;";

        // Specify the parameter value.
        int paramValue = 5;

        // Create and open the connection in a using block. This
        // ensures that all resources will be closed and disposed
        // when the code exits.
        using (SqlConnection connection =
            new SqlConnection(connectionString))
        {
            // Create the Command and Parameter objects.
            SqlCommand command = new SqlCommand(queryString, connection);
            command.Parameters.AddWithValue("@pricePoint", paramValue);

            // Open the connection in a try/catch block. 
            // Create and execute the DataReader, writing the result
            // set to the console window.
            try
            {
                connection.Open();
                SqlDataReader reader = command.ExecuteReader();
                while (reader.Read())
                {
                    Console.WriteLine("\t{0}\t{1}\t{2}",
                        reader[0], reader[1], reader[2]);
                }
                reader.Close();
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
            Console.ReadLine();
        }
    }

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OleDb

이 예제 코드에서는 Microsoft Access Northwind 샘플 데이터베이스에 연결할 수 있다고 가정합니다. 이 코드에서는 Products 테이블에서 행을 선택하는 OleDbCommand를 만들고 OleDbParameter를 추가하여 UnitPrice가 지정한 매개 변수 값(이 경우 5)보다 큰 행만 반환되도록 제한합니다. 코드가 종료될 때 리소스가 닫히고 삭제되도록 OleDbConnection이 using 블록 안에서 열립니다. 이 코드에서는 OleDbDataReader를 사용하여 명령을 실행하고 결과를 콘솔 창에 표시합니다.

Option Explicit On
Option Strict On

Imports System
Imports System.Data
Imports System.Data.OleDb

Public Class Program
    Public Shared Sub Main()

        ' The connection string assumes that the Access 
        ' Northwind.mdb is located in the c:\Data folder.
        Dim connectionString As String = _
             "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" _
            & "c:\Data\Northwind.mdb;User Id=admin;Password=;"

        ' Provide the query string with a parameter placeholder.
        Dim queryString As String = _
            "SELECT ProductID, UnitPrice, ProductName from Products " _
            & "WHERE UnitPrice > ? " _
            & "ORDER BY UnitPrice DESC;"

        ' Specify the parameter value.
        Dim paramValue As Integer = 5

        ' Create and open the connection in a using block. This
        ' ensures that all resources will be closed and disposed
        ' when the code exits.
        Using connection As New OleDbConnection(connectionString)

            ' Create the Command and Parameter objects.
            Dim command As New OleDbCommand(queryString, connection)
            command.Parameters.AddWithValue("@pricePoint", paramValue)

            ' Open the connection in a try/catch block. 
            ' Create and execute the DataReader, writing the result
            ' set to the console window.
            Try
                connection.Open()
                Dim dataReader As OleDbDataReader = _
                 command.ExecuteReader()
                Do While dataReader.Read()
                    Console.WriteLine( _
                        vbTab & "{0}" & vbTab & "{1}" & vbTab & "{2}", _
                     dataReader(0), dataReader(1), dataReader(2))
                Loop
                dataReader.Close()

            Catch ex As Exception
                Console.WriteLine(ex.Message)
            End Try
            Console.ReadLine()
        End Using
    End Sub
End Class

using System;
using System.Data;
using System.Data.OleDb;

class Program
{
    static void Main()
    {
        // The connection string assumes that the Access 
        // Northwind.mdb is located in the c:\Data folder.
        string connectionString =
        "Provider=Microsoft.Jet.OLEDB.4.0;Data Source="
            + "c:\\Data\\Northwind.mdb;User Id=admin;Password=;";

        // Provide the query string with a parameter placeholder.
        string queryString =
            "SELECT ProductID, UnitPrice, ProductName from products "
                + "WHERE UnitPrice > ? "
                + "ORDER BY UnitPrice DESC;";

        // Specify the parameter value.
        int paramValue = 5;

        // Create and open the connection in a using block. This
        // ensures that all resources will be closed and disposed
        // when the code exits.
        using (OleDbConnection connection =
            new OleDbConnection(connectionString))
        {
            // Create the Command and Parameter objects.
            OleDbCommand command = new OleDbCommand(queryString, connection);
            command.Parameters.AddWithValue("@pricePoint", paramValue);

            // Open the connection in a try/catch block. 
            // Create and execute the DataReader, writing the result
            // set to the console window.
            try
            {
                connection.Open();
                OleDbDataReader reader = command.ExecuteReader();
                while (reader.Read())
                {
                    Console.WriteLine("\t{0}\t{1}\t{2}",
                        reader[0], reader[1], reader[2]);
                }
                reader.Close();
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
            Console.ReadLine();
        }
    }

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Odbc

이 예제 코드에서는 Microsoft Access Northwind 샘플 데이터베이스에 연결할 수 있다고 가정합니다. 이 코드에서는 Products 테이블에서 행을 선택하는 OdbcCommand를 만들고 OdbcParameter를 추가하여 UnitPrice가 지정한 매개 변수 값(이 경우 5)보다 큰 행만 반환되도록 제한합니다. 코드가 종료될 때 리소스가 닫히고 삭제되도록 OdbcConnection이 using 블록 안에서 열립니다. 이 코드에서는 OdbcDataReader를 사용하여 명령을 실행하고 결과를 콘솔 창에 표시합니다.

Option Explicit On
Option Strict On

Imports System
Imports System.Data
Imports System.Data.Odbc

Public Class Program
    Public Shared Sub Main()

        ' The connection string assumes that the Access 
        ' Northwind.mdb is located in the c:\Data folder.
        Dim connectionString As String = _
            "Driver={Microsoft Access Driver (*.mdb)};" _
           & "Dbq=c:\Data\Northwind.mdb;Uid=Admin;Pwd=;"

        ' Provide the query string with a parameter placeholder.
        Dim queryString As String = _
            "SELECT ProductID, UnitPrice, ProductName from Products " _
            & "WHERE UnitPrice > ? " _
            & "ORDER BY UnitPrice DESC;"

        ' Specify the parameter value.
        Dim paramValue As Integer = 5

        ' Create and open the connection in a using block. This
        ' ensures that all resources will be closed and disposed
        ' when the code exits.
        Using connection As New OdbcConnection(connectionString)

            ' Create the Command and Parameter objects.
            Dim command As New OdbcCommand(queryString, connection)
            command.Parameters.AddWithValue("@pricePoint", paramValue)

            ' Open the connection in a try/catch block. 
            ' Create and execute the DataReader, writing the result
            ' set to the console window.
            Try
                connection.Open()
                Dim dataReader As OdbcDataReader = _
                 command.ExecuteReader()
                Do While dataReader.Read()
                    Console.WriteLine( _
                        vbTab & "{0}" & vbTab & "{1}" & vbTab & "{2}", _
                     dataReader(0), dataReader(1), dataReader(2))
                Loop
                dataReader.Close()

            Catch ex As Exception
                Console.WriteLine(ex.Message)
            End Try
            Console.ReadLine()
        End Using
    End Sub
End Class

using System;
using System.Data;
using System.Data.Odbc;

class Program
{
    static void Main()
    {
        // The connection string assumes that the Access 
        // Northwind.mdb is located in the c:\Data folder.
        string connectionString =
            "Driver={Microsoft Access Driver (*.mdb)};"
            + "Dbq=c:\\Data\\Northwind.mdb;Uid=Admin;Pwd=;";

        // Provide the query string with a parameter placeholder.
        string queryString =
            "SELECT ProductID, UnitPrice, ProductName from products "
                + "WHERE UnitPrice > ? "
                + "ORDER BY UnitPrice DESC;";

        // Specify the parameter value.
        int paramValue = 5;

        // Create and open the connection in a using block. This
        // ensures that all resources will be closed and disposed
        // when the code exits.
        using (OdbcConnection connection =
            new OdbcConnection(connectionString))
        {
            // Create the Command and Parameter objects.
            OdbcCommand command = new OdbcCommand(queryString, connection);
            command.Parameters.AddWithValue("@pricePoint", paramValue);

            // Open the connection in a try/catch block. 
            // Create and execute the DataReader, writing the result
            // set to the console window.
            try
            {
                connection.Open();
                OdbcDataReader reader = command.ExecuteReader();
                while (reader.Read())
                {
                    Console.WriteLine("\t{0}\t{1}\t{2}",
                        reader[0], reader[1], reader[2]);
                }
                reader.Close();
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
            Console.ReadLine();
        }
    }

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OracleClient

이 예제 코드에서는 Oracle 서버에서 DEMO.CUSTOMER에 연결할 수 있다고 가정합니다. 또한 System.Data.OracleClient.dll에 대한 참조를 추가해야 합니다. 이 코드는 OracleDataReader에 데이터를 반환합니다.

Option Explicit On
Option Strict On

Imports System
Imports System.Data
Imports System.Data.OracleClient

Public Class Program
    Public Shared Sub Main()

        Dim connectionString As String = _
            "Data Source=ThisOracleServer;Integrated Security=yes;"

        Dim queryString As String = _
            "SELECT CUSTOMER_ID, NAME FROM DEMO.CUSTOMER"

        Using connection As New OracleConnection(connectionString)
            Dim command As OracleCommand = connection.CreateCommand()
            command.CommandText = queryString
            Try
                connection.Open()
                Dim dataReader As OracleDataReader = _
                 command.ExecuteReader()
                Do While dataReader.Read()
                    Console.WriteLine(vbTab & "{0}" & vbTab & "{1}", _
                     dataReader(0), dataReader(1))
                Loop
                dataReader.Close()

            Catch ex As Exception
                Console.WriteLine(ex.Message)
            End Try
        End Using
    End Sub
End Class

using System;
using System.Data;
using System.Data.OracleClient;

class Program
{
    static void Main()
    {
        string connectionString = 
            "Data Source=ThisOracleServer;Integrated Security=yes;";
        string queryString =
            "SELECT CUSTOMER_ID, NAME FROM DEMO.CUSTOMER";
        using (OracleConnection connection =
                   new OracleConnection(connectionString))
        {
            OracleCommand command = connection.CreateCommand();
            command.CommandText = queryString;

            try
            {
                connection.Open();

                OracleDataReader reader = command.ExecuteReader();

                while (reader.Read())
                {
                    Console.WriteLine("\t{0}\t{1}",
                        reader[0], reader[1]);
                }
                reader.Close();
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
        }
    }
}

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Entity Framework 예제

다음에 나열된 코드에서는 EDM(엔터티 데이터 모델)의 엔터티를 쿼리하여 데이터 소스에서 데이터를 검색하는 방법을 보여 줍니다. 이러한 예제에서는 Northwind 모델을 사용합니다. 자세한 내용은 Introducing the Entity Framework를 참조하십시오.

LINQ to Entities

이 예제 코드에서는 LINQ 쿼리를 사용하여 CategoryID와 CategoryName 속성만 포함된 익명 형식으로 프로젝션된 Categories 개체로 데이터를 반환합니다. 자세한 내용은 LINQ to Entities Overview를 참조하십시오.

Option Explicit On
Option Strict On

Imports System
Imports System.Linq
Imports System.Data.Objects
Imports NorthwindModel

Class LinqSample
    Public Shared Sub ExecuteQuery()
        Using context As NorthwindEntities = New NorthwindEntities()
            Try
                Dim query = From category In context.Categories _
                            Select New With _
                            { _
                                .categoryID = category.CategoryID, _
                                .categoryName = category.CategoryName _
                            }

                For Each categoryInfo In query
                    Console.WriteLine(vbTab & "{0}" & vbTab & "{1}", _
                        categoryInfo.categoryID, categoryInfo.categoryName)
                Next
            Catch ex As Exception
                Console.WriteLine(ex.Message)
            End Try
        End Using
    End Sub
End Class

using System;
using System.Linq;
using System.Data.Objects;
using NorthwindModel;

class LinqSample
{
    public static void ExecuteQuery()
    {
        using (NorthwindEntities context = new NorthwindEntities())
        {
            try
            {
                var query = from category in context.Categories
                            select new
                            {
                                categoryID = category.CategoryID,
                                categoryName = category.CategoryName
                            };

                foreach (var categoryInfo in query)
                {
                    Console.WriteLine("\t{0}\t{1}",
                        categoryInfo.categoryID, categoryInfo.categoryName);
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
        }
    }
}

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형식화된 ObjectQuery

이 예제 코드에서는 ObjectQuery<T>을 사용하여 데이터를 Categories 개체로 반환합니다. 자세한 내용은 Object Queries (Entity Framework)를 참조하십시오.

Option Explicit On
Option Strict On

Imports System
Imports System.Data.Objects
Imports NorthwindModel

Class ObjectQuerySample
    Public Shared Sub ExecuteQuery()
        Using context As NorthwindEntities = New NorthwindEntities()
            Dim categoryQuery As ObjectQuery(Of Category) = context.Categories

            For Each category As Category In _
                categoryQuery.Execute(MergeOption.AppendOnly)
                Console.WriteLine(vbTab & "{0}" & vbTab & "{1}", _
                    category.CategoryID, category.CategoryName)
            Next
        End Using
    End Sub
End Class

using System;
using System.Data.Objects;
using NorthwindModel;

class ObjectQuerySample
{
    public static void ExecuteQuery()
    {
        using (NorthwindEntities context = new NorthwindEntities())
        {
            ObjectQuery<Category> categoryQuery = context.Categories;

            foreach (Category category in 
                categoryQuery.Execute(MergeOption.AppendOnly))
            {
                Console.WriteLine("\t{0}\t{1}",
                    category.CategoryID, category.CategoryName);
            }
        }
    }
}

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EntityClient

이 예제 코드에서는 EntityCommand를 사용하여 Entity SQL 쿼리를 실행합니다. 이 쿼리는 Categories 엔터티 형식의 인스턴스를 나타내는 레코드 목록을 반환합니다. EntityDataReader를 사용하여 결과 집합의 데이터 레코드에 액세스합니다. 자세한 내용은 EntityClient Provider for Entity Framework를 참조하십시오.

Option Explicit On
Option Strict On

Imports System
Imports System.Data
Imports System.Data.Common
Imports System.Data.EntityClient
Imports NorthwindModel

Class EntityClientSample
    Public Shared Sub ExecuteQuery()
        Dim queryString As String = _
            "SELECT c.CategoryID, c.CategoryName " & _
                "FROM NorthwindEntities.Categories AS c"

        Using conn As EntityConnection = _
            New EntityConnection("name=NorthwindEntities")

            Try
                conn.Open()
                Using query As EntityCommand = _
                New EntityCommand(queryString, conn)
                    Using rdr As DbDataReader = _
                        query.ExecuteReader(CommandBehavior.SequentialAccess)
                        While rdr.Read()
                            Console.WriteLine(vbTab & "{0}" & vbTab & "{1}", _
                                              rdr(0), rdr(1))
                        End While
                    End Using
                End Using
            Catch ex As Exception
                Console.WriteLine(ex.Message)
            End Try
        End Using 
    End Sub
End Class

using System;
using System.Data;
using System.Data.Common;
using System.Data.EntityClient;

class EntityClientSample
{
    public static void ExecuteQuery()
    {
        string queryString =
            @"SELECT c.CategoryID, c.CategoryName 
                FROM NorthwindEntities.Categories AS c";

        using (EntityConnection conn =
            new EntityConnection("name=NorthwindEntities"))
        {
            try
            {
                conn.Open();
                using (EntityCommand query = new EntityCommand(queryString, conn))
                {
                    using (DbDataReader rdr = 
                        query.ExecuteReader(CommandBehavior.SequentialAccess))
                    {
                        while (rdr.Read())
                        {
                            Console.WriteLine("\t{0}\t{1}", rdr[0], rdr[1]);
                        }
                    }
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
        }
    }
}

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LINQ to SQL

이 예제 코드에서는 LINQ 쿼리를 사용하여 CategoryID와 CategoryName 속성만 포함된 익명 형식으로 프로젝션된 Categories 개체로 데이터를 반환합니다. 이 예제는 Northwind 데이터 컨텍스트를 기반으로 합니다. 자세한 내용은 시작(LINQ to SQL)을 참조하십시오.

Option Explicit On
Option Strict On

Imports System
Imports System.Collections.Generic
Imports System.Linq
Imports System.Text
Imports Northwind

Class LinqSqlSample
    Public Shared Sub ExecuteQuery()
        Using db As NorthwindDataContext = New NorthwindDataContext()
            Try
                Dim query = From category In db.Categories _
                                Select New With _
                                { _
                                    .categoryID = category.CategoryID, _
                                    .categoryName = category.CategoryName _
                                }

                For Each categoryInfo In query
                    Console.WriteLine(vbTab & "{0}" & vbTab & "{1}", _
                            categoryInfo.categoryID, categoryInfo.categoryName)
                Next
            Catch ex As Exception
                Console.WriteLine(ex.Message)
            End Try
            End Using 
    End Sub
End Class

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Northwind;

    class LinqSqlSample
    {
        public static void ExecuteQuery()
        {
            using (NorthwindDataContext db = new NorthwindDataContext())
            {
                try
                {
                    var query = from category in db.Categories
                                select new
                                {
                                    categoryID = category.CategoryID,
                                    categoryName = category.CategoryName
                                };

                    foreach (var categoryInfo in query)
                    {
                        Console.WriteLine("vbTab {0} vbTab {1}",
                            categoryInfo.categoryID, categoryInfo.categoryName);
                    }
                }
                catch (Exception ex)
                {
                    Console.WriteLine(ex.Message);
                }
            }
        }
    }

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참고 항목

기타 리소스

ADO.NET 개요

ADO.NET에서 데이터 검색 및 수정

데이터 응용 프로그램 만들기

Querying an Entity Data Model (Entity Framework Tasks)

How to: Execute a Query that Returns an Anonymous Type (Entity Framework)