diff -r d3bfbce022aa -r 884ece10575d src/SqlHandler.h
--- a/src/SqlHandler.h	Fri Dec 13 22:19:41 2019 +0100
+++ b/src/SqlHandler.h	Sat Dec 14 14:00:36 2019 +0100
@@ -103,21 +103,25 @@
 		else throw SqlException(L"Unable to get SQLite column name.");
 	}
 
-	relpipe::writer::TypeId getColumType(int columnIndex) {
+	relpipe::writer::TypeId getColumType(int columnIndex, relpipe::writer::TypeId defaultType = relpipe::writer::TypeId::STRING) {
 		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 relpipe::writer::TypeId::STRING;
+		else return defaultType;
 		// TODO: support also other data types
 	}
 
@@ -202,8 +206,13 @@
 		}
 	}
 
+	relpipe::writer::TypeId findType(string_t columnName, int columnIndex, const Statement& statement, std::shared_ptr<PreparedStatement> preparedStatement) {
+		for (TypeCast typeCast : statement.typeCasts) if (typeCast.name == columnName) return relationalWriter->toTypeId(typeCast.type);
+		return preparedStatement->getColumType(columnIndex);
+	}
+
 	void processStatement(const Statement& statement) {
-		std::unique_ptr<PreparedStatement> prepared(connection->prepareStatement(convertor.to_bytes(statement.sql).c_str()));
+		std::shared_ptr<PreparedStatement> prepared(connection->prepareStatement(convertor.to_bytes(statement.sql).c_str()));
 		int columnCount = prepared->getColumnCount();
 		int parameterCount = statement.parameters.size();
 
@@ -212,7 +221,10 @@
 		}
 
 		std::vector<relpipe::writer::AttributeMetadata> metadata;
-		for (int i = 0; i < columnCount; i++) metadata.push_back({convertor.from_bytes(prepared->getColumName(i).c_str()), prepared->getColumType(i)});
+		for (int i = 0; i < columnCount; i++) {
+			string_t columnName = convertor.from_bytes(prepared->getColumName(i).c_str());
+			metadata.push_back({columnName, findType(columnName, i, statement, prepared)});
+		}
 		relationalWriter->startRelation(statement.relation, metadata, true);
 
 		while (prepared->next()) {