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Add more code samples for documentation - Transaction and GetSchema (#824)
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‎doc/samples/SqlConnection_GetSchema_Restriction.cs

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// <Snippet1>
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using System;
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using System.Data;
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using Microsoft.Data.SqlClient;
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class Program
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{
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static void Main(string[] args)
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{
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string connectionString = "Data Source = localhost; Integrated Security = true; Initial Catalog = AdventureWorks";
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using (SqlConnection connection = new SqlConnection(connectionString))
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{
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connection.Open();
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// Specify the restrictions.
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string[] restrictions = new string[4];
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restrictions[1] = "Sales";
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System.Data.DataTable table = connection.GetSchema("Tables", restrictions);
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// Display the contents of the table.
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DisplayData(table);
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Console.WriteLine("Press any key to continue.");
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Console.ReadKey();
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}
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}
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private static void DisplayData(System.Data.DataTable table)
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{
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foreach (System.Data.DataRow row in table.Rows)
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{
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foreach (System.Data.DataColumn col in table.Columns)
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{
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Console.WriteLine("{0} = {1}", col.ColumnName, row[col]);
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}
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Console.WriteLine("============================");
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}
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}
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}
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// </Snippet1>

‎doc/samples/SqlConnection_GetSchema_Tables.cs

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// <Snippet1>
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using System;
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using System.Data;
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using Microsoft.Data.SqlClient;
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class Program
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{
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static void Main(string[] args)
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{
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string connectionString = "Data Source = localhost; Integrated Security = true; Initial Catalog = AdventureWorks";
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using (SqlConnection connection = new SqlConnection(connectionString))
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{
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connection.Open();
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DataTable table = connection.GetSchema("Tables");
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// Display the contents of the table.
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DisplayData(table);
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Console.WriteLine("Press any key to continue.");
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Console.ReadKey();
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}
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}
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private static void DisplayData(System.Data.DataTable table)
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{
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foreach (System.Data.DataRow row in table.Rows)
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{
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foreach (System.Data.DataColumn col in table.Columns)
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{
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Console.WriteLine("{0} = {1}", col.ColumnName, row[col]);
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}
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Console.WriteLine("============================");
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}
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}
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}
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// </Snippet1>

‎doc/samples/SqlDataAdapter_Concurrency.cs

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// <Snippet1>
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using System;
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using System.Data;
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using Microsoft.Data.SqlClient;
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class Program
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{
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static void Main(string[] args)
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{
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string connectionString = "Data Source = localhost; Integrated Security = true; Initial Catalog = Northwind";
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using (SqlConnection connection = new SqlConnection(connectionString))
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{
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// Assumes connection is a valid SqlConnection.
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SqlDataAdapter adapter = new SqlDataAdapter(
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"SELECT CustomerID, CompanyName FROM Customers ORDER BY CustomerID",
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connection);
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// The Update command checks for optimistic concurrency violations
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// in the WHERE clause.
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adapter.UpdateCommand = new SqlCommand("UPDATE Customers Set CustomerID = @CustomerID, CompanyName = @CompanyName " +
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"WHERE CustomerID = @oldCustomerID AND CompanyName = @oldCompanyName", connection);
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adapter.UpdateCommand.Parameters.Add(
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"@CustomerID", SqlDbType.NChar, 5, "CustomerID");
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adapter.UpdateCommand.Parameters.Add(
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"@CompanyName", SqlDbType.NVarChar, 30, "CompanyName");
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// Pass the original values to the WHERE clause parameters.
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SqlParameter parameter = adapter.UpdateCommand.Parameters.Add(
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"@oldCustomerID", SqlDbType.NChar, 5, "CustomerID");
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parameter.SourceVersion = DataRowVersion.Original;
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parameter = adapter.UpdateCommand.Parameters.Add(
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"@oldCompanyName", SqlDbType.NVarChar, 30, "CompanyName");
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parameter.SourceVersion = DataRowVersion.Original;
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// Add the RowUpdated event handler.
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adapter.RowUpdated += new SqlRowUpdatedEventHandler(OnRowUpdated);
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DataSet dataSet = new DataSet();
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adapter.Fill(dataSet, "Customers");
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// Modify the DataSet contents.
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adapter.Update(dataSet, "Customers");
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foreach (DataRow dataRow in dataSet.Tables["Customers"].Rows)
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{
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if (dataRow.HasErrors)
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Console.WriteLine(dataRow[0] + "\n" + dataRow.RowError);
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}
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}
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}
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protected static void OnRowUpdated(object sender, SqlRowUpdatedEventArgs args)
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{
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if (args.RecordsAffected == 0)
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{
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args.Row.RowError = "Optimistic Concurrency Violation Encountered";
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args.Status = UpdateStatus.SkipCurrentRow;
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}
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}
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}
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// </Snippet1>

‎doc/samples/SqlTransactionLocal.cs

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// <Snippet1>
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using System;
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using Microsoft.Data.SqlClient;
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class Program
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{
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static void Main(string[] args)
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{
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string connectionString = "Data Source = localhost; Integrated Security = true; Initial Catalog = AdventureWorks";
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using (SqlConnection connection = new SqlConnection(connectionString))
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{
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connection.Open();
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// Start a local transaction.
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SqlTransaction sqlTran = connection.BeginTransaction();
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// Enlist a command in the current transaction.
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SqlCommand command = connection.CreateCommand();
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command.Transaction = sqlTran;
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try
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{
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// Execute two separate commands.
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command.CommandText =
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"INSERT INTO Production.ScrapReason(Name) VALUES('Wrong size')";
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command.ExecuteNonQuery();
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command.CommandText =
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"INSERT INTO Production.ScrapReason(Name) VALUES('Wrong color')";
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command.ExecuteNonQuery();
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// Commit the transaction.
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sqlTran.Commit();
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Console.WriteLine("Both records were written to database.");
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}
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catch (Exception ex)
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{
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// Handle the exception if the transaction fails to commit.
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Console.WriteLine(ex.Message);
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try
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{
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// Attempt to roll back the transaction.
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sqlTran.Rollback();
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}
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catch (Exception exRollback)
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{
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// Throws an InvalidOperationException if the connection
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// is closed or the transaction has already been rolled
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// back on the server.
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Console.WriteLine(exRollback.Message);
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}
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}
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}
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}
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}
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// </Snippet1>

‎doc/samples/SqlTransactionScope.cs

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// <Snippet1>
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using System;
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using System.Transactions;
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using Microsoft.Data.SqlClient;
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class Program
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{
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static void Main(string[] args)
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{
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string connectionString = "Data Source = localhost; Integrated Security = true; Initial Catalog = AdventureWorks";
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string commandText1 = "INSERT INTO Production.ScrapReason(Name) VALUES('Wrong size')";
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string commandText2 = "INSERT INTO Production.ScrapReason(Name) VALUES('Wrong color')";
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int result = CreateTransactionScope(connectionString, connectionString, commandText1, commandText2);
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Console.WriteLine("result = " + result);
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}
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static public int CreateTransactionScope(string connectString1, string connectString2,
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string commandText1, string commandText2)
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{
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// Initialize the return value to zero and create a StringWriter to display results.
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int returnValue = 0;
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System.IO.StringWriter writer = new System.IO.StringWriter();
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// Create the TransactionScope in which to execute the commands, guaranteeing
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// that both commands will commit or roll back as a single unit of work.
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using (TransactionScope scope = new TransactionScope())
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{
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using (SqlConnection connection1 = new SqlConnection(connectString1))
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{
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try
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{
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// Opening the connection automatically enlists it in the
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// TransactionScope as a lightweight transaction.
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connection1.Open();
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// Create the SqlCommand object and execute the first command.
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SqlCommand command1 = new SqlCommand(commandText1, connection1);
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returnValue = command1.ExecuteNonQuery();
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writer.WriteLine("Rows to be affected by command1: {0}", returnValue);
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// if you get here, this means that command1 succeeded. By nesting
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// the using block for connection2 inside that of connection1, you
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// conserve server and network resources by opening connection2
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// only when there is a chance that the transaction can commit.
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using (SqlConnection connection2 = new SqlConnection(connectString2))
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try
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{
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// The transaction is promoted to a full distributed
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// transaction when connection2 is opened.
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connection2.Open();
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// Execute the second command in the second database.
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returnValue = 0;
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SqlCommand command2 = new SqlCommand(commandText2, connection2);
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returnValue = command2.ExecuteNonQuery();
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writer.WriteLine("Rows to be affected by command2: {0}", returnValue);
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}
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catch (Exception ex)
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{
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// Display information that command2 failed.
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writer.WriteLine("returnValue for command2: {0}", returnValue);
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writer.WriteLine("Exception Message2: {0}", ex.Message);
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}
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}
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catch (Exception ex)
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{
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// Display information that command1 failed.
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writer.WriteLine("returnValue for command1: {0}", returnValue);
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writer.WriteLine("Exception Message1: {0}", ex.Message);
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}
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}
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// If an exception has been thrown, Complete will not
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// be called and the transaction is rolled back.
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scope.Complete();
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}
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// The returnValue is greater than 0 if the transaction committed.
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if (returnValue > 0)
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{
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writer.WriteLine("Transaction was committed.");
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}
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else
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{
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// You could write additional business logic here, notify the caller by
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// throwing a TransactionAbortedException, or log the failure.
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writer.WriteLine("Transaction rolled back.");
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}
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// Display messages.
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Console.WriteLine(writer.ToString());
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return returnValue;
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}
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}
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// </Snippet1>

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