Report RecordsAffected according to ADO.NET

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

@@ -535,4 +535,60 @@ 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);
+		}
+	}
+
+	[Test]
+	public async Task RecordsAffectedForInsertReturningTest()
+	{
+		// INSERT ... RETURNING is classified by Firebird as a stored procedure execution, not as an INSERT.
+		await using (var transaction = await Connection.BeginTransactionAsync())
+		{
+			await using (var command = new FbCommand("insert into test (int_field) values (100001) returning int_field", Connection, transaction))
+			{
+				await using (var reader = await command.ExecuteReaderAsync())
+				{
+					while (await reader.ReadAsync())
+					{ }
+					Assert.AreEqual(1, reader.RecordsAffected);
+				}
+			}
+			await transaction.RollbackAsync();
+		}
+	}
+
+	[Test]
+	public async Task ExecuteNonQueryForStatementWithoutRowChangesIsMinusOneTest()
+	{
+		// Stored procedure execution that changes no rows keeps the -1 of "all other types of statements".
+		await using (var command = new FbCommand("execute block as begin end", Connection))
+		{
+			Assert.AreEqual(-1, await command.ExecuteNonQueryAsync());
+		}
+	}
+
+	[Test]
+	public async Task ExecuteNonQueryForInsertReturningTest()
+	{
+		await using (var transaction = await Connection.BeginTransactionAsync())
+		{
+			await using (var command = new FbCommand("insert into test (int_field) values (100002) returning int_field", Connection, transaction))
+			{
+				Assert.AreEqual(1, await command.ExecuteNonQueryAsync());
+			}
+			await transaction.RollbackAsync();
+		}
+	}
 }

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

@@ -263,6 +263,27 @@ 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").
+	/// Firebird classifies INSERT ... RETURNING and DML inside an execute block as stored procedure execution; the server's
+	/// count is reported for those only when it is positive, so procedures that change no rows keep -1.
+	/// </summary>
+	internal int StatementRecordsAffected
+	{
+		get
+		{
+			return _statement?.StatementType switch
+			{
+				DbStatementType.Insert => RecordsAffected,
+				DbStatementType.Update => RecordsAffected,
+				DbStatementType.Delete => RecordsAffected,
+				DbStatementType.StoredProcedure when RecordsAffected > 0 => RecordsAffected,
+				_ => -1,
+			};
+		}
+	}
+
 	internal bool IsDisposed
 	{
 		get { return _disposed; }
@@ -529,13 +550,7 @@ 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 +581,7 @@ 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

@@ -84,6 +84,7 @@ internal FbDataReader(FbCommand command, FbConnection connection, CommandBehavio
 		_connection = connection;
 		_commandBehavior = commandBehavior;
 		_fields = _command.GetFieldsDescriptor();
+		_recordsAffected = -1;
 
 		UpdateRecordsAffected();
 	}
@@ -1016,10 +1017,11 @@ 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;
 			}
 		}
 	}