diff -r ec793cb3e686 -r 49919a60c747 src/PreparedStatement.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/PreparedStatement.cpp	Wed Dec 25 00:57:26 2019 +0100
@@ -0,0 +1,102 @@
+/**
+ * Relational pipes
+ * Copyright © 2019 František Kučera (Frantovo.cz, GlobalCode.info)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, version 3.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "PreparedStatement.h"
+
+namespace relpipe {
+namespace tr {
+namespace sql {
+
+PreparedStatement::PreparedStatement(sqlite3_stmt* stmt) : stmt(stmt) {
+}
+
+PreparedStatement::~PreparedStatement() {
+	sqlite3_finalize(stmt);
+}
+
+void PreparedStatement::setBoolean(int parameterIndex, relpipe::reader::boolean_t value) {
+	int result = sqlite3_bind_int(stmt, parameterIndex, value);
+	if (result != SQLITE_OK) throw SqlException(L"Unable to set SQLite parameter.");
+}
+
+void PreparedStatement::setInteger(int parameterIndex, relpipe::reader::integer_t value) {
+	int result = sqlite3_bind_int64(stmt, parameterIndex, value);
+	if (result != SQLITE_OK) throw SqlException(L"Unable to set SQLite parameter.");
+}
+
+void PreparedStatement::setString(int parameterIndex, std::string value) {
+	int result = sqlite3_bind_text(stmt, parameterIndex, value.c_str(), -1, SQLITE_TRANSIENT);
+	if (result != SQLITE_OK) throw SqlException(L"Unable to set SQLite parameter.");
+}
+
+void PreparedStatement::setNull(int parameterIndex) {
+	int result = sqlite3_bind_null(stmt, parameterIndex);
+	if (result != SQLITE_OK) throw SqlException(L"Unable to set SQLite parameter.");
+}
+
+bool PreparedStatement::next() {
+	int result = sqlite3_step(stmt);
+	if (result == SQLITE_ROW) return true;
+	else if (result == SQLITE_DONE) return false;
+	else throw SqlException(L"Error while iterating over SQLite result.");
+}
+
+void PreparedStatement::reset() {
+	int result = sqlite3_reset(stmt);
+	if (result != SQLITE_OK) throw SqlException(L"Unable to reset SQLite prepared statement.");
+}
+
+int PreparedStatement::getColumnCount() {
+	return sqlite3_column_count(stmt);
+}
+
+std::string PreparedStatement::getColumName(int columnIndex) {
+	const char* name = sqlite3_column_name(stmt, columnIndex);
+	if (name) return name;
+	else throw SqlException(L"Unable to get SQLite column name.");
+}
+
+relpipe::writer::TypeId PreparedStatement::getColumType(int columnIndex, relpipe::writer::TypeId defaultType) {
+	const char* type = sqlite3_column_decltype(stmt, columnIndex);
+
+	// TODO: sqlite3_column_decltype returns value only for columns of existing tables, not for dynamic expressions – SQLite uses dynamic types
+	// maybe we could write a function/module that returns result set metadata for given query (before executing it)
+	// or use at least explicit casts in SQL and modify sqlite3_column_decltype() function or add some new one to return such casted type
+	// 
+	// fprintf(stderr, "%d → %s\n", columnIndex, type);
+	// SELECT typeof(1+1); == "integer"
+	// https://www.sqlite.org/c3ref/column_decltype.html – sqlite3_column_decltype
+	// https://www.sqlite.org/c3ref/column_blob.html – sqlite3_column_type
+	// https://www.sqlite.org/datatype3.html – Datatypes In SQLite Version 3
+	// https://dba.stackexchange.com/questions/203220/sqlite-what-is-the-use-of-specifying-data-types
+	// https://www.mail-archive.com/sqlite-users@mailinglists.sqlite.org/msg118093.html
+
+	if (type == nullptr) return relpipe::writer::TypeId::STRING;
+	else if (strcmp(type, "integer") == 0) return relpipe::writer::TypeId::INTEGER;
+	else if (strcmp(type, "text") == 0) return relpipe::writer::TypeId::STRING;
+	else return defaultType;
+	// TODO: support also other data types
+}
+
+std::string PreparedStatement::getString(int columnIndex) {
+	const char* value = (const char*) sqlite3_column_text(stmt, columnIndex);
+		return value ? value : ""; // TODO: support NULL values (when supported in relpipe format)
+}
+
+}
+}
+}