Load column whose name begins with @. Fixes #1365

Author: bgrainger

src/MySqlConnector/MySqlBulkCopy.cs

@@ -265,7 +265,7 @@ private async ValueTask<MySqlBulkCopyResult> WriteToServerAsync(IOBehavior ioBeh
 			{
 				if (columnMapping.DestinationColumn.Length == 0)
 					throw new InvalidOperationException($"MySqlBulkCopyColumnMapping.DestinationName is not set for SourceOrdinal {columnMapping.SourceOrdinal}");
-				if (columnMapping.DestinationColumn[0] == '@')
+				if (columnMapping.DestinationColumn[0] == '@' && columnMapping.Expression is not null)
 					bulkLoader.Columns.Add(columnMapping.DestinationColumn);
 				else
 					bulkLoader.Columns.Add(QuoteIdentifier(columnMapping.DestinationColumn));

tests/IntegrationTests/BulkLoaderSync.cs

@@ -530,7 +530,6 @@ public void BulkCopyNullDataTable()
 		Assert.Throws<ArgumentNullException>(() => bulkCopy.WriteToServer(default(DataTable)));
 	}
 
-#if !MYSQL_DATA
 	[Fact]
 	public void BulkCopyDataTableWithMySqlDecimal()
 	{
@@ -655,7 +654,6 @@ public void BulkCopyDataTableWithTimeOnly()
 			Assert.Equal(new TimeOnly(1, 2, 3, 456), reader.GetTimeOnly(2));
 		}
 	}
-#endif
 #endif
 
 	public static IEnumerable<object[]> GetBulkCopyData() =>
@@ -713,6 +711,50 @@ public void BulkCopyDataTable(string columnType, object[] rows)
 		}
 	}
 
+	[Fact]
+	public void BulkCopyToColumnNeedingQuoting()
+	{
+		var dataTable = new DataTable()
+		{
+			Columns =
+			{
+				new DataColumn("id", typeof(int)),
+				new DataColumn("@a", typeof(string)),
+			},
+		};
+		dataTable.Rows.Add(2, "two");
+
+		using var connection = new MySqlConnection(GetLocalConnectionString());
+		connection.Open();
+		using (var cmd = new MySqlCommand($"""
+			drop table if exists bulk_load_quoted_identifier;
+			create table bulk_load_quoted_identifier(id int, `@a` text);
+			insert into bulk_load_quoted_identifier values (1, 'one');
+			""", connection))
+		{
+			cmd.ExecuteNonQuery();
+		}
+
+		var bulkCopy = new MySqlBulkCopy(connection)
+		{
+			DestinationTableName = "bulk_load_quoted_identifier",
+		};
+		var result = bulkCopy.WriteToServer(dataTable);
+		Assert.Equal(1, result.RowsInserted);
+		Assert.Empty(result.Warnings);
+
+		using (var cmd = new MySqlCommand(@"select `@a` from bulk_load_quoted_identifier order by id;", connection))
+		{
+			using var reader = cmd.ExecuteReader();
+			Assert.True(reader.Read());
+			Assert.Equal("one", reader.GetString(0));
+			Assert.True(reader.Read());
+			Assert.Equal("two", reader.GetString(0));
+			Assert.False(reader.Read());
+			Assert.False(reader.NextResult());
+		}
+	}
+
 	[Fact]
 	public void BulkCopyDataTableWithLongBlob()
 	{