Report RecordsAffected according to ADO.NET

src/FirebirdSql.Data.FirebirdClient.Tests/FbDataReaderTests.cs

@@ -535,4 +535,18 @@ public async Task GetFieldValueTest()
 			await transaction.RollbackAsync();
 		}
 	}
+
+	[Test]
+	public async Task RecordsAffectedIsMinusOneForSelectTest()
+	{
+		// DbDataReader.RecordsAffected: "-1 for SELECT statements; 0 if no rows were affected or the statement failed."
+		await using (var command = new FbCommand("select INT_FIELD from TEST where 1 = 0", Connection))
+		{
+			var reader = await command.ExecuteReaderAsync();
+			while (await reader.ReadAsync())
+			{ }
+			await reader.CloseAsync();
+			Assert.AreEqual(-1, reader.RecordsAffected);
+		}
+	}
 }

src/FirebirdSql.Data.FirebirdClient/FirebirdClient/FbCommand.cs

@@ -263,6 +263,24 @@ internal int RecordsAffected
 		}
 	}
 
+	/// <summary>
+	/// The rows an INSERT, UPDATE or DELETE affected, or -1 for any other statement (DbCommand.ExecuteNonQuery: "For all
+	/// other types of statements, the return value is -1"; DbDataReader.RecordsAffected: "-1 for SELECT statements").
+	/// </summary>
+	internal int StatementRecordsAffected
+	{
+		get
+		{
+			return _statement?.StatementType switch
+			{
+				DbStatementType.Insert => RecordsAffected,
+				DbStatementType.Update => RecordsAffected,
+				DbStatementType.Delete => RecordsAffected,
+				_ => -1,
+			};
+		}
+	}
+
 	internal bool IsDisposed
 	{
 		get { return _disposed; }
@@ -529,13 +547,7 @@ public override int ExecuteNonQuery()
 			}
 		}
 
-		return _statement.StatementType switch
-		{
-			DbStatementType.Insert => RecordsAffected,
-			DbStatementType.Update => RecordsAffected,
-			DbStatementType.Delete => RecordsAffected,
-			_ => -1,
-		};
+		return StatementRecordsAffected;
 	}
 	public override async Task<int> ExecuteNonQueryAsync(CancellationToken cancellationToken)
 	{
@@ -566,13 +578,7 @@ public override async Task<int> ExecuteNonQueryAsync(CancellationToken cancellat
 			}
 		}
 
-		return _statement.StatementType switch
-		{
-			DbStatementType.Insert => RecordsAffected,
-			DbStatementType.Update => RecordsAffected,
-			DbStatementType.Delete => RecordsAffected,
-			_ => -1,
-		};
+		return StatementRecordsAffected;
 	}
 
 	public new FbDataReader ExecuteReader() => ExecuteReader(CommandBehavior.Default);

src/FirebirdSql.Data.FirebirdClient/FirebirdClient/FbDataReader.cs

@@ -51,7 +51,7 @@ public sealed class FbDataReader : DbDataReader
 	private bool _eof;
 	private bool _isClosed;
 	private int _position;
-	private int _recordsAffected;
+	private int _recordsAffected = -1;
 	private Dictionary<string, int> _columnsIndexesOrdinal;
 	private Dictionary<string, int> _columnsIndexesOrdinalCI;
 
@@ -1016,10 +1016,11 @@ private void UpdateRecordsAffected()
 	{
 		if (_command != null && !_command.IsDisposed)
 		{
-			if (_command.RecordsAffected != -1)
+			var recordsAffected = _command.StatementRecordsAffected;
+			if (recordsAffected != -1)
 			{
 				_recordsAffected = _recordsAffected == -1 ? 0 : _recordsAffected;
-				_recordsAffected += _command.RecordsAffected;
+				_recordsAffected += recordsAffected;
 			}
 		}
 	}