Extract SQLExtendedFetch implementation

Fix comments and use `ARROW_UNUSED`

Use nullptr explicitly

Co-Authored-By: alinalibq <alina.li@improving.com>

Author: alinaliBQ

cpp/src/arrow/flight/sql/odbc/odbc_api.cc

@@ -1076,8 +1076,33 @@ SQLRETURN SQLExtendedFetch(SQLHSTMT stmt, SQLUSMALLINT fetch_orientation,
                    << ", row_count_ptr: " << static_cast<const void*>(row_count_ptr)
                    << ", row_status_array: "
                    << static_cast<const void*>(row_status_array);
-  // GH-47714 TODO: Implement SQLExtendedFetch
-  return SQL_INVALID_HANDLE;
+
+  using ODBC::ODBCDescriptor;
+  using ODBC::ODBCStatement;
+  return ODBCStatement::ExecuteWithDiagnostics(stmt, SQL_ERROR, [=]() {
+    // Only SQL_FETCH_NEXT forward-only fetching orientation is supported,
+    // meaning the behavior of SQLExtendedFetch is same as SQLFetch.
+    if (fetch_orientation != SQL_FETCH_NEXT) {
+      throw DriverException("Optional feature not supported.", "HYC00");
+    }
+    // Ignore fetch_offset as it's not applicable to SQL_FETCH_NEXT
+    ARROW_UNUSED(fetch_offset);
+
+    ODBCStatement* statement = reinterpret_cast<ODBCStatement*>(stmt);
+
+    // The SQL_ROWSET_SIZE statement attribute specifies the number of rows in the
+    // rowset. Retrieve it from GetRowsetSize.
+    SQLULEN row_set_size = statement->GetRowsetSize();
+    ARROW_LOG(DEBUG) << "SQL_ROWSET_SIZE value for SQLExtendedFetch: " << row_set_size;
+
+    if (statement->Fetch(static_cast<size_t>(row_set_size), row_count_ptr,
+                         row_status_array)) {
+      return SQL_SUCCESS;
+    } else {
+      // Reached the end of rowset
+      return SQL_NO_DATA;
+    }
+  });
 }
 
 SQLRETURN SQLFetchScroll(SQLHSTMT stmt, SQLSMALLINT fetch_orientation,

cpp/src/arrow/flight/sql/odbc/odbc_impl/odbc_statement.cc

@@ -316,7 +316,8 @@ void ODBCStatement::ExecuteDirect(const std::string& query) {
   is_prepared_ = false;
 }
 
-bool ODBCStatement::Fetch(size_t rows) {
+bool ODBCStatement::Fetch(size_t rows, SQLULEN* row_count_ptr,
+                          SQLUSMALLINT* row_status_array) {
   if (has_reached_end_of_result_) {
     ird_->SetRowsProcessed(0);
     return false;
@@ -349,11 +350,24 @@ bool ODBCStatement::Fetch(size_t rows) {
     current_ard_->NotifyBindingsHavePropagated();
   }
 
-  size_t rows_fetched = current_result_->Move(rows, current_ard_->GetBindOffset(),
-                                              current_ard_->GetBoundStructOffset(),
-                                              ird_->GetArrayStatusPtr());
+  uint16_t* array_status_ptr;
+  if (row_status_array) {
+    // For SQLExtendedFetch only
+    array_status_ptr = row_status_array;
+  } else {
+    array_status_ptr = ird_->GetArrayStatusPtr();
+  }
+
+  size_t rows_fetched =
+      current_result_->Move(rows, current_ard_->GetBindOffset(),
+                            current_ard_->GetBoundStructOffset(), array_status_ptr);
   ird_->SetRowsProcessed(static_cast<SQLULEN>(rows_fetched));
 
+  if (row_count_ptr) {
+    // For SQLExtendedFetch only
+    *row_count_ptr = rows_fetched;
+  }
+
   row_number_ += rows_fetched;
   has_reached_end_of_result_ = rows_fetched != rows;
   return rows_fetched != 0;

cpp/src/arrow/flight/sql/odbc/odbc_impl/odbc_statement.h

@@ -59,7 +59,11 @@ class ODBCStatement : public ODBCHandle<ODBCStatement> {
   void ExecuteDirect(const std::string& query);
 
   /// \brief Return true if the number of rows fetch was greater than zero.
-  bool Fetch(size_t rows);
+  ///
+  /// row_count_ptr and row_status_array are optional arguments, they are only needed for
+  /// SQLExtendedFetch
+  bool Fetch(size_t rows, SQLULEN* row_count_ptr = 0, SQLUSMALLINT* row_status_array = 0);
+
   bool IsPrepared() const;
 
   void GetStmtAttr(SQLINTEGER statement_attribute, SQLPOINTER output,

cpp/src/arrow/flight/sql/odbc/tests/statement_test.cc

@@ -1722,6 +1722,83 @@ TYPED_TEST(StatementTest, TestSQLBindColIndicatorOnlySQLUnbind) {
   // EXPECT_EQ(1, char_val_ind);
 }
 
+TYPED_TEST(StatementTest, TestSQLExtendedFetchRowFetching) {
+  // Set SQL_ROWSET_SIZE to fetch 3 rows at once
+
+  constexpr SQLULEN rows = 3;
+  SQLINTEGER val[rows];
+  SQLLEN buf_len = sizeof(val);
+  SQLLEN ind[rows];
+
+  // Same variable will be used for column 1, the value of `val`
+  // should be updated after every SQLFetch call.
+  ASSERT_EQ(SQL_SUCCESS, SQLBindCol(this->stmt, 1, SQL_C_LONG, val, buf_len, ind));
+
+  ASSERT_EQ(SQL_SUCCESS, SQLSetStmtAttr(this->stmt, SQL_ROWSET_SIZE,
+                                        reinterpret_cast<SQLPOINTER>(rows), 0));
+
+  std::wstring wsql =
+      LR"(
+   SELECT 1 AS small_table
+   UNION ALL
+   SELECT 2
+   UNION ALL
+   SELECT 3;
+ )";
+  std::vector<SQLWCHAR> sql0(wsql.begin(), wsql.end());
+
+  ASSERT_EQ(SQL_SUCCESS,
+            SQLExecDirect(this->stmt, &sql0[0], static_cast<SQLINTEGER>(sql0.size())));
+
+  // Fetch row 1-3.
+  SQLULEN row_count;
+  SQLUSMALLINT row_status[rows];
+
+  ASSERT_EQ(SQL_SUCCESS,
+            SQLExtendedFetch(this->stmt, SQL_FETCH_NEXT, 0, &row_count, row_status));
+  EXPECT_EQ(3, row_count);
+
+  for (int i = 0; i < rows; i++) {
+    EXPECT_EQ(SQL_SUCCESS, row_status[i]);
+  }
+
+  // Verify 1 is returned for row 1
+  EXPECT_EQ(1, val[0]);
+  // Verify 2 is returned for row 2
+  EXPECT_EQ(2, val[1]);
+  // Verify 3 is returned for row 3
+  EXPECT_EQ(3, val[2]);
+
+  // Verify result set has no more data beyond row 3
+  SQLULEN row_count2;
+  SQLUSMALLINT row_status2[rows];
+  EXPECT_EQ(SQL_NO_DATA,
+            SQLExtendedFetch(this->stmt, SQL_FETCH_NEXT, 0, &row_count2, row_status2));
+}
+
+TEST_F(StatementRemoteTest, DISABLED_TestSQLExtendedFetchQueryNullIndicator) {
+  // GH-47110: SQLExtendedFetch should return SQL_SUCCESS_WITH_INFO for 22002
+  // Limitation on mock test server prevents null from working properly, so use remote
+  // server instead. Mock server has type `DENSE_UNION` for null column data.
+  SQLINTEGER val;
+
+  ASSERT_EQ(SQL_SUCCESS, SQLBindCol(this->stmt, 1, SQL_C_LONG, &val, 0, nullptr));
+
+  std::wstring wsql = L"SELECT null as null_col;";
+  std::vector<SQLWCHAR> sql0(wsql.begin(), wsql.end());
+
+  ASSERT_EQ(SQL_SUCCESS,
+            SQLExecDirect(this->stmt, &sql0[0], static_cast<SQLINTEGER>(sql0.size())));
+
+  SQLULEN row_count1;
+  SQLUSMALLINT row_status1[1];
+
+  // SQLExtendedFetch should return SQL_SUCCESS_WITH_INFO for 22002 state
+  ASSERT_EQ(SQL_SUCCESS_WITH_INFO,
+            SQLExtendedFetch(this->stmt, SQL_FETCH_NEXT, 0, &row_count1, row_status1));
+  VerifyOdbcErrorState(SQL_HANDLE_STMT, this->stmt, kErrorState22002);
+}
+
 TYPED_TEST(StatementTest, TestSQLNativeSqlReturnsInputString) {
   SQLWCHAR buf[1024];
   SQLINTEGER buf_char_len = sizeof(buf) / GetSqlWCharSize();