diff --git a/executor.cpp b/executor.cpp
index fe09c46..5f96dbe 100644
--- a/executor.cpp
+++ b/executor.cpp
@@ -103,37 +103,7 @@ bool Executor::execute_select(SelectFromTableNode& node) {
 
     for (auto row = begin (table->m_rows); row != end (table->m_rows); ++row) {
         // eval where for row
-        bool where_true = true;
-        if (node.where->node_type == NodeType::true_node) {    // no where clause
-            where_true = true;
-        } else {    // evaluate where
-            RelationalOperatorNode& filter = static_cast<RelationalOperatorNode &>(*node.where);
-            if (filter.op == RelationalOperatorType::greater) {
-                std::unique_ptr<Node> left_value;
-                if ((*filter.left).node_type == NodeType::database_value) {
-                    DatabaseValueNode *dvl = static_cast<DatabaseValueNode*>(filter.left.get());
-                    ColDefNode col_def = table->get_column_def(dvl->col_name); // TODO optimize it to just get this def once
-                    auto db_value = row->ithColum(col_def.order);
-                    if (col_def.type == ColumnType::integer_type) {
-                        left_value = std::make_unique<IntValueNode>(db_value->integerValue());
-                    }
-                    // TODO other cases
-                }
-
-                std::unique_ptr<Node> right_value;
-                if ((*filter.right).node_type == NodeType::int_value) {
-                    IntValueNode *ivl = static_cast<IntValueNode*>(filter.right.get());
-                    right_value = std::make_unique<IntValueNode>(ivl->value);
-                }
-
-                IntValueNode* left_int_value = static_cast<IntValueNode *>(left_value.get());
-                IntValueNode* right_int_value = static_cast<IntValueNode *>(right_value.get());
-
-                where_true = left_int_value->value > right_int_value->value;
-            }
-        }
-
-        if (where_true) {
+        if (evalWhere(node, table, row)) {
             // prepare empty row
             Row new_row = result.createEmptyRow();
 
@@ -159,3 +129,70 @@ bool Executor::execute_select(SelectFromTableNode& node) {
     return true;
 }
 
+bool Executor::evalWhere(const SelectFromTableNode &node, Table *table,
+                         std::vector<Row, std::allocator<Row>>::iterator &row) const {
+    if (node.where->node_type == NodeType::true_node) {    // no where clause
+        return true;
+    }
+
+    if (node.where.get()->node_type == NodeType::relational_operator) {
+        RelationalOperatorNode &filter = static_cast<RelationalOperatorNode &>(*node.where);
+        return evalRelationalOperator(filter, table, row);
+    }
+
+//    if (node.where.get()->node_type == NodeType::logical_operator) {
+//        LogicalOperatorNode &filter = static_cast<LogicalOperatorNode &>(*node.where);
+//        return evalLogicalOperator(filter, table, row);
+//    }
+
+    return false;
+}
+
+bool Executor::evalRelationalOperator(const RelationalOperatorNode &filter, Table *table, std::vector<Row, std::allocator<Row>>::iterator &row) const {
+    std::unique_ptr<Node> left_value = evalNode(table, row, filter.left.get());
+    std::unique_ptr<Node> right_value = evalNode(table, row, filter.right.get());
+
+    if (left_value->node_type == NodeType::int_value) {
+        // zjisti typy a vzit hodnoty k porovnani
+    }
+
+    IntValueNode *left_int_value = static_cast<IntValueNode *>(left_value.get());
+    IntValueNode *right_int_value = static_cast<IntValueNode *>(right_value.get());
+
+    if (filter.op == RelationalOperatorType::greater) {
+        return left_int_value->value > right_int_value->value;
+    }
+
+    if (filter.op == RelationalOperatorType::equal) {
+        return left_int_value->value == right_int_value->value;
+    }
+
+    throw Exception("invalid relational operator");
+}
+
+std::unique_ptr<Node> Executor::evalNode(Table *table, std::vector<Row, std::allocator<Row>>::iterator &row, Node *filter) const {
+    if (filter->node_type == NodeType::database_value) {
+        DatabaseValueNode *dvl = static_cast<DatabaseValueNode *>(filter);
+        ColDefNode col_def = table->get_column_def(dvl->col_name); // TODO optimize it to just get this def once
+        auto db_value = row->ithColum(col_def.order);
+        if (col_def.type == ColumnType::integer_type) {
+            return std::make_unique<IntValueNode>(db_value->integerValue());
+        }
+        // TODO other cases
+
+    } else if (filter->node_type == NodeType::int_value) {
+        IntValueNode *ivl = static_cast<IntValueNode *>(filter);
+        return std::make_unique<IntValueNode>(ivl->value);
+
+    } else if (filter->node_type == NodeType::float_value) {
+        FloatValueNode *ivl = static_cast<FloatValueNode*>(filter);
+        return std::make_unique<FloatValueNode>(ivl->value);
+
+    } else if (filter->node_type == NodeType::string_value) {
+        StringValueNode *ivl = static_cast<StringValueNode*>(filter);
+        return std::make_unique<StringValueNode>(ivl->value);
+    }
+
+    throw Exception("invalid type");
+}
+
diff --git a/executor.h b/executor.h
index b77fcd7..0ef4689 100644
--- a/executor.h
+++ b/executor.h
@@ -22,4 +22,13 @@ private:
 private:
     std::vector<Table>  m_tables;
 
+    bool evalWhere(const SelectFromTableNode &node, Table *table,
+                   std::vector<Row, std::allocator<Row>>::iterator &row) const;
+
+    std::unique_ptr<Node>
+    evalNode(Table *table, std::vector<Row, std::allocator<Row>>::iterator &row,
+             Node *filter) const;
+
+    bool evalRelationalOperator(const RelationalOperatorNode &filter, Table *table,
+                                std::vector<Row, std::allocator<Row>>::iterator &row) const;
 };