GH-47713: [C++][FlightRPC] ODBC return number of result columns

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

@@ -890,8 +890,13 @@ SQLRETURN SQLNumResultCols(SQLHSTMT stmt, SQLSMALLINT* column_count_ptr) {
   ARROW_LOG(DEBUG) << "SQLNumResultCols called with stmt: " << stmt
                    << ", column_count_ptr: "
                    << static_cast<const void*>(column_count_ptr);
-  // GH-47713 TODO: Implement SQLNumResultCols
-  return SQL_INVALID_HANDLE;
+
+  using ODBC::ODBCStatement;
+  return ODBCStatement::ExecuteWithDiagnostics(stmt, SQL_ERROR, [=]() {
+    ODBCStatement* statement = reinterpret_cast<ODBCStatement*>(stmt);
+    statement->GetColumnCount(column_count_ptr);
+    return SQL_SUCCESS;
+  });
 }
 
 SQLRETURN SQLRowCount(SQLHSTMT stmt, SQLLEN* row_count_ptr) {

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

@@ -735,6 +735,16 @@ bool ODBCStatement::GetData(SQLSMALLINT record_number, SQLSMALLINT c_type,
                                   data_ptr, buffer_length, indicator_ptr);
 }
 
+void ODBCStatement::GetColumnCount(SQLSMALLINT* column_count_ptr) {
+  if (!column_count_ptr) {
+    // column count pointer is not valid, do nothing as ODBC spec does not mention this as
+    // an error
+    return;
+  }
+  size_t column_count = ird_->GetRecords().size();
+  *column_count_ptr = static_cast<SQLSMALLINT>(column_count);
+}
+
 void ODBCStatement::ReleaseStatement() {
   CloseCursor(true);
   connection_.DropStatement(this);

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

@@ -80,6 +80,9 @@ class ODBCStatement : public ODBCHandle<ODBCStatement> {
   bool GetData(SQLSMALLINT record_number, SQLSMALLINT c_type, SQLPOINTER data_ptr,
                SQLLEN buffer_length, SQLLEN* indicator_ptr);
 
+  /// \brief Return number of columns from data set
+  void GetColumnCount(SQLSMALLINT* column_count_ptr);
+
   /**
    * @brief Closes the cursor. This does _not_ un-prepare the statement or change
    * bindings.

cpp/src/arrow/flight/sql/odbc/tests/CMakeLists.txt

@@ -35,6 +35,7 @@ add_arrow_test(flight_sql_odbc_test
                odbc_test_suite.cc
                odbc_test_suite.h
                connection_test.cc
+               statement_test.cc
                # Enable Protobuf cleanup after test execution
                # GH-46889: move protobuf_test_util to a more common location
                ../../../../engine/substrait/protobuf_test_util.cc

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

@@ -0,0 +1,84 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+#include "arrow/flight/sql/odbc/tests/odbc_test_suite.h"
+
+#include "arrow/flight/sql/odbc/odbc_impl/platform.h"
+
+#include <sql.h>
+#include <sqltypes.h>
+#include <sqlucode.h>
+
+#include <limits>
+
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+
+namespace arrow::flight::sql::odbc {
+
+template <typename T>
+class StatementTest : public T {};
+
+class StatementMockTest : public FlightSQLODBCMockTestBase {};
+class StatementRemoteTest : public FlightSQLODBCRemoteTestBase {};
+using TestTypes = ::testing::Types<StatementMockTest, StatementRemoteTest>;
+TYPED_TEST_SUITE(StatementTest, TestTypes);
+
+TYPED_TEST(StatementTest, SQLNumResultColsReturnsColumnsOnSelect) {
+  SQLSMALLINT column_count = 0;
+  SQLSMALLINT expected_value = 3;
+  SQLWCHAR sql_query[] = L"SELECT 1 AS col1, 'One' AS col2, 3 AS col3";
+  SQLINTEGER query_length = static_cast<SQLINTEGER>(wcslen(sql_query));
+
+  ASSERT_EQ(SQL_SUCCESS, SQLExecDirect(this->stmt, sql_query, query_length));
+
+  ASSERT_EQ(SQL_SUCCESS, SQLFetch(this->stmt));
+
+  CheckIntColumn(this->stmt, 1, 1);
+  CheckStringColumnW(this->stmt, 2, L"One");
+  CheckIntColumn(this->stmt, 3, 3);
+
+  ASSERT_EQ(SQL_SUCCESS, SQLNumResultCols(this->stmt, &column_count));
+
+  EXPECT_EQ(expected_value, column_count);
+}
+
+TYPED_TEST(StatementTest, SQLNumResultColsReturnsSuccessOnNullptr) {
+  SQLWCHAR sql_query[] = L"SELECT 1 AS col1, 'One' AS col2, 3 AS col3";
+  SQLINTEGER query_length = static_cast<SQLINTEGER>(wcslen(sql_query));
+
+  ASSERT_EQ(SQL_SUCCESS, SQLExecDirect(this->stmt, sql_query, query_length));
+
+  ASSERT_EQ(SQL_SUCCESS, SQLFetch(this->stmt));
+
+  CheckIntColumn(this->stmt, 1, 1);
+  CheckStringColumnW(this->stmt, 2, L"One");
+  CheckIntColumn(this->stmt, 3, 3);
+
+  ASSERT_EQ(SQL_SUCCESS, SQLNumResultCols(this->stmt, nullptr));
+}
+
+TYPED_TEST(StatementTest, SQLNumResultColsFunctionSequenceErrorOnNoQuery) {
+  SQLSMALLINT column_count = 0;
+  SQLSMALLINT expected_value = 0;
+
+  ASSERT_EQ(SQL_ERROR, SQLNumResultCols(this->stmt, &column_count));
+  VerifyOdbcErrorState(SQL_HANDLE_STMT, this->stmt, kErrorStateHY010);
+
+  EXPECT_EQ(expected_value, column_count);
+}
+
+}  // namespace arrow::flight::sql::odbc