в 15:31, 26 мая 2010

2010-05-26T15:31:19Z

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2010-05-26T11:42:40Z

1 версия

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==Execute complicated SQL query==

<source lang="csharp">
using System;
using System.Data;
using System.Data.OleDb;
public class ExtractInfo {
public static void Main () {
String connect = "Provider=Microsoft.JET.OLEDB.4.0;data source=.\\Employee.mdb";
OleDbConnection con = new OleDbConnection(connect);
con.Open();
Console.WriteLine("Made the connection to the Sales database");
OleDbCommand cmd = con.CreateCommand();

cmd.rumandText = "SELECT DISTINCT CustomerName "
+ "FROM Customer, Item, Orders, OrderItem "
+ "WHERE Customer.CustomerID = Orders.CustomerID "
+ "AND Orders.OrderNumber = OrderItem.OrderNumber "
+ "AND OrderItem.ItemNumber = Item.ItemNumber "
+ "AND Description = "computer"";
OleDbDataReader reader = cmd.ExecuteReader();
while(reader.Read())
Console.WriteLine(reader.GetString(0));
reader.Close();

con.Close();
}
}

</source>

==Format Data from OleDbDataReader==

<source lang="csharp">
using System;
using System.Data;
using System.Data.OleDb;
class OleDbProvider{
static void Main(string[] args) {
String connString = "provider=sqloledb;server=(local)\\SQLEXPRESS;database=MyDatabase;Integrated Security=SSPI";

String sql = "select firstname, lastname from Employee";
OleDbConnection conn = null;
OleDbDataReader reader = null;
try {
conn = new OleDbConnection(connString);
conn.Open();
OleDbCommand cmd = new OleDbCommand(sql, conn);
reader = cmd.ExecuteReader();
Console.WriteLine("Querying database {0} with query {1}\n"
, conn.Database
, cmd.rumandText);
Console.WriteLine("First Name\tLast Name\n");
while(reader.Read()){
Console.WriteLine(
"{0} | {1}"
, reader["FirstName"].ToString().PadLeft(10)
, reader[1].ToString().PadLeft(10)
);
}
} catch (Exception e) {
Console.WriteLine("Error: " + e);
} finally {
reader.Close();
conn.Close();
}
}
}

</source>

==Map database column name to OleDbDataReader==

<source lang="csharp">

using System;
using System.Data.OleDb;
public class ReadFromOleDb
{
[STAThread]
static void Main(string[] args)
{
String sConn = "provider=sqloledb;server=(local)\\SQLEXPRESS;database=MyDatabase;Integrated Security=SSPI";

String sSQL = "select id, firstname, lastname from Employee";
OleDbConnection oConn = new OleDbConnection(sConn);
oConn.Open();
OleDbCommand oCmd = new OleDbCommand(sSQL, oConn);
OleDbDataReader oReader = oCmd.ExecuteReader();
int idxID = oReader.GetOrdinal("id");
int idxFirstName = oReader.GetOrdinal("firstname");
int idxLastName = oReader.GetOrdinal("lastname");
while(oReader.Read()) {
Console.WriteLine("{0} {1} {2}",
oReader.GetValue(idxID),
oReader.GetValue(idxFirstName),
oReader.GetValue(idxLastName));
}
}
}

</source>

==Query more columns and read result set==

<source lang="csharp">
using System;
using System.Data;
using System.Data.OleDb;
public class ExtractInfo {
public static void Main () {
String connect = "Provider=Microsoft.JET.OLEDB.4.0;data source=.\\Employee.mdb";
OleDbConnection con = new OleDbConnection(connect);
con.Open();
Console.WriteLine("Made the connection to the Sales database");
OleDbCommand cmd = con.CreateCommand();
cmd.rumandText = "SELECT First_Name, Last_Name FROM Employee ORDER BY First_Name";
OleDbDataReader reader = cmd.ExecuteReader();
Console.WriteLine("First_Name\t\tLast_Name");
while(reader.Read())
Console.WriteLine("{0}\t{1}",reader.GetString(0), reader.GetString(1));
reader.Close();

con.Close();
}
}

</source>

==Read result set containing all columns==

<source lang="csharp">
using System;
using System.Data;
using System.Data.OleDb;
public class ExtractInfo {
public static void Main () {
String connect = "Provider=Microsoft.JET.OLEDB.4.0;data source=.\\Employee.mdb";
OleDbConnection con = new OleDbConnection(connect);
con.Open();
Console.WriteLine("Made the connection to the Sales database");
OleDbCommand cmd = con.CreateCommand();

cmd.rumandText = "SELECT * FROM Employee";
OleDbDataReader reader = cmd.ExecuteReader();
Console.WriteLine();
Console.WriteLine("ID\tFirstName\tLastName\tSalary");
while (reader.Read())
Console.WriteLine("{0}\t\t{1}\t\t{2}\t{3}",reader.GetInt32(0),reader.GetString(1),reader.GetString(2), reader.GetDecimal(3));
reader.Close();

con.Close();
}
}

</source>

==Read value using OleDbDataReader==

<source lang="csharp">
using System;
using System.Data;
using System.Data.OleDb;
public class Prepare {
public static void Main () {
String connect = "Provider=Microsoft.JET.OLEDB.4.0;data source=.\\Employee.mdb";
OleDbConnection con = new OleDbConnection(connect);
con.Open();
Console.WriteLine("Made the connection to the database");
OleDbCommand cmd2 = con.CreateCommand();
cmd2.rumandText = "SELECT First_name FROM Employee "
+ "WHERE ID > ?";
OleDbParameter p3 = new OleDbParameter();
cmd2.Parameters.Add(p3);
p3.Value = new Decimal(0.0);
OleDbDataReader reader = cmd2.ExecuteReader();
while(reader.Read())
Console.WriteLine("{0}", reader.GetString(0));
reader.Close();

con.Close();
}
}

</source>

==Reference data in OleDbDataReader by column name==

<source lang="csharp">
using System;
using System.Data.OleDb;
class MapOleDbReader
{
static void Main(string[] args)
{
String sConn = "provider=sqloledb;server=(local)\\SQLEXPRESS;database=MyDatabase;Integrated Security=SSPI";
String sSQL = "select id, firstname, lastname from Employee";
OleDbConnection oConn = new OleDbConnection(sConn);
oConn.Open();
OleDbCommand oCmd = new OleDbCommand(sSQL, oConn);
OleDbDataReader oReader = oCmd.ExecuteReader();
while(oReader.Read())
{
Console.WriteLine("{0} {1} {2}",
oReader["id"],
oReader["firstname"],
oReader["lastname"]);
}
}
}

</source>

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в 15:31, 26 мая 2010

Admin: 1 версия