diff --git a/src/observer/sql/executor/delete_operator.h b/src/observer/sql/executor/delete_operator.h
index 6a4ac77261c4dd8e8f011be85d131003a5fc9e03..983229463af964e1db70f6b1eeeca664166988d9 100644
--- a/src/observer/sql/executor/delete_operator.h
+++ b/src/observer/sql/executor/delete_operator.h
@@ -35,6 +35,15 @@ public:
   Tuple * current_tuple() override {
     return nullptr;
   }
+  int tuple_cell_num() const override
+  {
+    return 0;
+  }
+
+  RC tuple_cell_spec_at(int index, TupleCellSpec &spec) const override
+  {
+    return RC::NOTFOUND;
+  }
 private:
   DeleteStmt *delete_stmt_ = nullptr;
 };
diff --git a/src/observer/sql/executor/execute_stage.cpp b/src/observer/sql/executor/execute_stage.cpp
index 0d830b68deec388cd67c239201700aed7511db5c..12479041039ec9a040a0f87af1d56bb94fa1675c 100644
--- a/src/observer/sql/executor/execute_stage.cpp
+++ b/src/observer/sql/executor/execute_stage.cpp
@@ -29,6 +29,7 @@ See the Mulan PSL v2 for more details. */
 #include "sql/executor/table_scan_operator.h"
 #include "sql/executor/predicate_operator.h"
 #include "sql/executor/delete_operator.h"
+#include "sql/executor/project_operator.h"
 #include "sql/stmt/stmt.h"
 #include "sql/stmt/select_stmt.h"
 #include "sql/stmt/update_stmt.h"
@@ -216,6 +217,25 @@ void end_trx_if_need(Session *session, Trx *trx, bool all_right)
   }
 }
 
+void print_tuple_header(std::ostream &os, const Operator &oper)
+{
+  const int cell_num = oper.tuple_cell_num();
+  TupleCellSpec cell_spec;
+  for (int i = 0; i < cell_num; i++) {
+    oper.tuple_cell_spec_at(i, cell_spec);
+    if (i != 0) {
+      os << " | ";
+    }
+
+    if (cell_spec.alias()) {
+      os << cell_spec.alias();
+    }
+  }
+
+  if (cell_num > 0) {
+    os << '\n';
+  }
+}
 void tuple_to_string(std::ostream &os, const Tuple &tuple)
 {
   TupleCell cell;
@@ -249,17 +269,25 @@ RC ExecuteStage::do_select(SQLStageEvent *sql_event)
 
   Table *table = select_stmt->tables().front();
   TableScanOperator table_scan_operator(table);
-  rc = table_scan_operator.open();
+  PredicateOperator pred_oper(select_stmt->filter_stmt());
+  pred_oper.add_child(&table_scan_operator);
+  ProjectOperator project_oper;
+  project_oper.add_child(&pred_oper);
+  for (const FieldDesc &field : select_stmt->query_fields()) {
+    project_oper.add_projection(field.table_, field.field_meta_);
+  }
+  rc = project_oper.open();
   if (rc != RC::SUCCESS) {
     LOG_WARN("failed to open operator");
     return rc;
   }
 
   std::stringstream ss;
-  while ((rc = table_scan_operator.next()) == RC::SUCCESS) {
+  print_tuple_header(ss, project_oper);
+  while ((rc = project_oper.next()) == RC::SUCCESS) {
     // get current record
     // write to response
-    Tuple * tuple = table_scan_operator.current_tuple();
+    Tuple * tuple = project_oper.current_tuple();
     if (nullptr == tuple) {
       rc = RC::INTERNAL;
       LOG_WARN("failed to get current record. rc=%s", strrc(rc));
@@ -272,9 +300,9 @@ RC ExecuteStage::do_select(SQLStageEvent *sql_event)
 
   if (rc != RC::RECORD_EOF) {
     LOG_WARN("something wrong while iterate operator. rc=%s", strrc(rc));
-    table_scan_operator.close();
+    project_oper.close();
   } else {
-    rc = table_scan_operator.close();
+    rc = project_oper.close();
   }
   session_event->set_response(ss.str());
   return rc;
diff --git a/src/observer/sql/executor/operator.h b/src/observer/sql/executor/operator.h
index 11dd64aa5cbb8849caaa268ce049861e49d38d27..16c3afde21956e298ae0b4bb86a058bd35383c7a 100644
--- a/src/observer/sql/executor/operator.h
+++ b/src/observer/sql/executor/operator.h
@@ -19,6 +19,7 @@ See the Mulan PSL v2 for more details. */
 #include "sql/executor/tuple.h"
 
 class Record;
+class TupleCellSpec;
 
 class Operator
 {
@@ -33,11 +34,14 @@ public:
   virtual RC close() = 0;
 
   virtual Tuple * current_tuple() = 0;
+  virtual int tuple_cell_num() const = 0;
+  virtual RC  tuple_cell_spec_at(int index, TupleCellSpec &spec) const = 0;
 
   void add_child(Operator *oper) {
     children_.push_back(oper);
   }
 
+
 protected:
   std::vector<Operator *> children_;
 };
diff --git a/src/observer/sql/executor/predicate_operator.cpp b/src/observer/sql/executor/predicate_operator.cpp
index efbb20ad6d8e348eb4aa38b9553d2e1a8f453290..9648250fe558df35bd9fe3f21230f8fedbd9582a 100644
--- a/src/observer/sql/executor/predicate_operator.cpp
+++ b/src/observer/sql/executor/predicate_operator.cpp
@@ -74,7 +74,7 @@ void get_cell(const RowTuple &tuple, const FilterItem &filter_item, TupleCell &c
 
 bool PredicateOperator::do_predicate(RowTuple &tuple)
 {
-  if (filter_stmt_ == nullptr) {
+  if (filter_stmt_ == nullptr || filter_stmt_->filter_units().empty()) {
     return true;
   }
 
@@ -102,3 +102,12 @@ bool PredicateOperator::do_predicate(RowTuple &tuple)
   }
   return false;
 }
+
+int PredicateOperator::tuple_cell_num() const
+{
+  return children_[0]->tuple_cell_num();
+}
+RC PredicateOperator::tuple_cell_spec_at(int index, TupleCellSpec &spec) const
+{
+  return children_[0]->tuple_cell_spec_at(index, spec);
+}
diff --git a/src/observer/sql/executor/predicate_operator.h b/src/observer/sql/executor/predicate_operator.h
index 551848fba6e1d8a4be7d17bdba91de29527e7e6a..acc35398afa1b567e70778948abca3eefd8bb6b7 100644
--- a/src/observer/sql/executor/predicate_operator.h
+++ b/src/observer/sql/executor/predicate_operator.h
@@ -31,6 +31,8 @@ public:
   RC close() override;
 
   Tuple * current_tuple() override;
+  int tuple_cell_num() const override;
+  RC tuple_cell_spec_at(int index, TupleCellSpec &spec) const override;
 private:
   bool do_predicate(RowTuple &tuple);
 private:
diff --git a/src/observer/sql/executor/project_operator.cpp b/src/observer/sql/executor/project_operator.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..396a1c1c33d40c349243f9ad8e1f322893fd3bae
--- /dev/null
+++ b/src/observer/sql/executor/project_operator.cpp
@@ -0,0 +1,62 @@
+/* Copyright (c) 2021 Xie Meiyi(xiemeiyi@hust.edu.cn) and OceanBase and/or its affiliates. All rights reserved.
+miniob is licensed under Mulan PSL v2.
+You can use this software according to the terms and conditions of the Mulan PSL v2.
+You may obtain a copy of Mulan PSL v2 at:
+         http://license.coscl.org.cn/MulanPSL2
+THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND,
+EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT,
+MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.
+See the Mulan PSL v2 for more details. */
+
+//
+// Created by WangYunlai on 2022/07/01.
+//
+
+#include "common/log/log.h"
+#include "sql/executor/project_operator.h"
+#include "storage/common/record.h"
+#include "storage/common/table.h"
+
+RC ProjectOperator::open()
+{
+  if (children_.size() != 1) {
+    LOG_WARN("project operator must has 1 child");
+    return RC::INTERNAL;
+  }
+
+  Operator *child = children_[0];
+  RC rc = child->open();
+  if (rc != RC::SUCCESS) {
+    LOG_WARN("failed to open child operator: %s", strrc(rc));
+    return rc;
+  }
+
+  return RC::SUCCESS;
+}
+
+RC ProjectOperator::next()
+{
+  return children_[0]->next();
+}
+
+RC ProjectOperator::close()
+{
+  children_[0]->close();
+  return RC::SUCCESS;
+}
+Tuple *ProjectOperator::current_tuple()
+{
+  tuple_.set_tuple(children_[0]->current_tuple());
+  return &tuple_;
+}
+
+void ProjectOperator::add_projection(const Table *table, const FieldMeta *field_meta)
+{
+  TupleCellSpec spec(table->name(), field_meta->name(), field_meta->name());
+  tuple_.add_cell_spec(spec);
+}
+
+RC ProjectOperator::tuple_cell_spec_at(int index, TupleCellSpec &spec) const
+{
+  return tuple_.cell_spec_at(index, spec);
+}
diff --git a/src/observer/sql/executor/project_operator.h b/src/observer/sql/executor/project_operator.h
new file mode 100644
index 0000000000000000000000000000000000000000..0ac687d34512d36acbc524f3d3ee24f517e31eb7
--- /dev/null
+++ b/src/observer/sql/executor/project_operator.h
@@ -0,0 +1,44 @@
+/* Copyright (c) 2021 Xie Meiyi(xiemeiyi@hust.edu.cn) and OceanBase and/or its affiliates. All rights reserved.
+miniob is licensed under Mulan PSL v2.
+You can use this software according to the terms and conditions of the Mulan PSL v2.
+You may obtain a copy of Mulan PSL v2 at:
+         http://license.coscl.org.cn/MulanPSL2
+THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND,
+EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT,
+MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.
+See the Mulan PSL v2 for more details. */
+
+//
+// Created by WangYunlai on 2022/07/01.
+//
+
+#pragma once
+
+#include "sql/executor/operator.h"
+#include "rc.h"
+
+class ProjectOperator : public Operator
+{
+public:
+  ProjectOperator()
+  {}
+
+  virtual ~ProjectOperator() = default;
+
+  void add_projection(const Table *table, const FieldMeta *field); // TODO how to handle the memory in tupleCellSpec?
+
+  RC open() override;
+  RC next() override;
+  RC close() override;
+
+  int tuple_cell_num() const override
+  {
+    return tuple_.cell_num();
+  }
+
+  RC tuple_cell_spec_at(int index, TupleCellSpec &spec) const override;
+
+  Tuple * current_tuple() override;
+private:
+  ProjectTuple tuple_;
+};
diff --git a/src/observer/sql/executor/table_scan_operator.cpp b/src/observer/sql/executor/table_scan_operator.cpp
index 3d407b75174923ddfb02d953c53032b543d03a84..c4354da1608d70d6a445573096679ceeb5c23cd9 100644
--- a/src/observer/sql/executor/table_scan_operator.cpp
+++ b/src/observer/sql/executor/table_scan_operator.cpp
@@ -47,3 +47,7 @@ Tuple * TableScanOperator::current_tuple()
   tuple_.set_record(&current_record_);
   return &tuple_;
 }
+RC TableScanOperator::tuple_cell_spec_at(int index, TupleCellSpec &spec) const
+{
+  return tuple_.cell_spec_at(index, spec);
+}
diff --git a/src/observer/sql/executor/table_scan_operator.h b/src/observer/sql/executor/table_scan_operator.h
index 88eb3008635d99e4fbbe23ad23ff93b8f9c59bd0..19a3092c04f03e44887149fe6a46809c50b1ce06 100644
--- a/src/observer/sql/executor/table_scan_operator.h
+++ b/src/observer/sql/executor/table_scan_operator.h
@@ -36,6 +36,13 @@ public:
   RC close() override;
 
   Tuple * current_tuple() override;
+
+  int tuple_cell_num() const override
+  {
+    return tuple_.cell_num();
+  }
+
+  RC tuple_cell_spec_at(int index, TupleCellSpec &spec) const override;
 private:
   Table *table_ = nullptr;
   RecordFileScanner record_scanner_;
diff --git a/src/observer/sql/executor/tuple.h b/src/observer/sql/executor/tuple.h
index 8ad6f887d445b1a9d8e79da9dcba7c0b787ce5f6..35afdca08127beff08478e0ed4c5929ebc5f193c 100644
--- a/src/observer/sql/executor/tuple.h
+++ b/src/observer/sql/executor/tuple.h
@@ -27,7 +27,50 @@ class Table;
 
 class TupleCellSpec
 {
-  
+public:
+  TupleCellSpec() = default;
+  TupleCellSpec(const char *table_name, const char *field_name, const char *alias)
+    : table_name_(table_name), field_name_(field_name), alias_(alias)
+  {}
+
+  void set_table_name(const char *table_name)
+  {
+    this->table_name_ = table_name;
+  }
+
+  void set_field_name(const char *field_name)
+  {
+    this->field_name_ = field_name;
+  }
+
+  void set_alias(const char *alias)
+  {
+    this->alias_ = alias;
+  }
+  const char *table_name() const
+  {
+    return table_name_;
+  }
+  const char *field_name() const
+  {
+    return field_name_;
+  }
+  const char *alias() const
+  {
+    return alias_;
+  }
+
+  bool is_same_cell(const TupleCellSpec &other) const
+  {
+    return 0 == strcmp(this->table_name_, other.table_name_) &&
+      0 == strcmp(this->field_name_, other.field_name_);
+  }
+
+private:
+  // TODO table and field cannot describe all scenerio, should be expression
+  const char *table_name_ = nullptr;
+  const char *field_name_ = nullptr;
+  const char *alias_ = nullptr;
 };
 
 class Tuple
@@ -38,8 +81,9 @@ public:
 
   virtual int cell_num() const = 0; 
   virtual RC  cell_at(int index, TupleCell &cell) const = 0;
+  virtual RC  find_cell(const TupleCellSpec &spec, TupleCell &cell) const = 0;
 
-  //virtual RC  cell_spec_at(int index, TupleCellSpec &spec) const;
+  virtual RC  cell_spec_at(int index, TupleCellSpec &spec) const = 0;
 };
 
 class RowTuple : public Tuple
@@ -82,14 +126,33 @@ public:
     return RC::SUCCESS;
   }
 
-  RC cell_spec_at(int index, TupleCellSpec &spec) const
+  RC find_cell(const TupleCellSpec &spec, TupleCell &cell) const override
+  {
+    const char *table_name = spec.table_name();
+    if (0 != strcmp(table_name, table_->name())) {
+      return RC::NOTFOUND;
+    }
+
+    const char *field_name = spec.field_name();
+    for (int i = 0; i < fields_->size(); ++i) {
+      const FieldMeta &field_meta = (*fields_)[i];
+      if (0 == strcmp(field_name, field_meta.name())) {
+	return cell_at(i, cell);
+      }
+    }
+    return RC::NOTFOUND;
+  }
+
+  RC cell_spec_at(int index, TupleCellSpec &spec) const override
   {
     if (index < 0 || index >= fields_->size()) {
       LOG_WARN("invalid argument. index=%d", index);
       return RC::INVALID_ARGUMENT;
     }
     const FieldMeta &field_meta = (*fields_)[index];
-    // TODO
+    spec.set_table_name(table_->name());
+    spec.set_field_name(field_meta.name());
+    spec.set_alias(field_meta.name());
     return RC::SUCCESS;
   }
 
@@ -112,7 +175,59 @@ private:
 class CompositeTuple : public Tuple
 {
 public:
+  int cell_num() const override; 
+  RC  cell_at(int index, TupleCell &cell) const = 0;
 private:
+  int cell_num_ = 0;
   std::vector<Tuple *> tuples_;
 };
 */
+
+class ProjectTuple : public Tuple
+{
+public:
+  ProjectTuple() = default;
+
+  void set_tuple(Tuple *tuple)
+  {
+    this->tuple_ = tuple;
+  }
+
+  void add_cell_spec(const TupleCellSpec &spec)
+  {
+    speces_.push_back(spec);
+  }
+  int cell_num() const override
+  {
+    return speces_.size();
+  }
+
+  RC cell_at(int index, TupleCell &cell) const override
+  {
+    if (index < 0 || index >= speces_.size()) {
+      return RC::GENERIC_ERROR;
+    }
+    if (tuple_ == nullptr) {
+      return RC::GENERIC_ERROR;
+    }
+
+    const TupleCellSpec &spec = speces_[index]; // TODO better: add mapping between projection and raw tuple
+    return tuple_->find_cell(spec, cell);
+  }
+
+  RC find_cell(const TupleCellSpec &spec, TupleCell &cell) const override
+  {
+    return tuple_->find_cell(spec, cell);
+  }
+  RC cell_spec_at(int index, TupleCellSpec &spec) const override
+  {
+    if (index < 0 || index >= speces_.size()) {
+      return RC::NOTFOUND;
+    }
+    spec = speces_[index];
+    return RC::SUCCESS;
+  }
+private:
+  std::vector<TupleCellSpec> speces_;
+  Tuple *tuple_ = nullptr;
+};
diff --git a/src/observer/sql/stmt/select_stmt.h b/src/observer/sql/stmt/select_stmt.h
index df4f91f8debc5e8aa7255dcd16f82aaecf21d008..6d8fa3c6a2f482eb5a83614edcae97529f7cea57 100644
--- a/src/observer/sql/stmt/select_stmt.h
+++ b/src/observer/sql/stmt/select_stmt.h
@@ -24,7 +24,7 @@ class FilterStmt;
 class Db;
 class Table;
 
-// better to create a field class 
+// TODO better to create a field class 
 struct FieldDesc
 {
   Table *table_ = nullptr;
@@ -47,6 +47,7 @@ public:
 
 public:
   const std::vector<Table *> &tables() const { return tables_; }
+  const std::vector<FieldDesc> &query_fields() const { return query_fields_; }
   FilterStmt *filter_stmt() const { return filter_stmt_; }
 
 private: