FIX: Invalid data type for None

mssql_python/pybind/ddbc_bindings.cpp

@@ -2335,6 +2335,33 @@ SQLRETURN BindParameterArray(SQLHANDLE hStmt, const py::list& columnwise_params,
                     bufferLength = sizeof(SQLGUID);
                     break;
                 }
+                case SQL_C_DEFAULT: {
+                    // Handle NULL parameters - all values in this column should be NULL
+                    LOG("BindParameterArray: Binding SQL_C_DEFAULT (NULL) array - param_index=%d, count=%zu", paramIndex, paramSetSize);
+
+                    // Verify all values are indeed NULL
+                    for (size_t i = 0; i < paramSetSize; ++i) {
+                        if (!columnValues[i].is_none()) {
+                            LOG("BindParameterArray: SQL_C_DEFAULT non-NULL value detected - param_index=%d, row=%zu", paramIndex, i);
+                            ThrowStdException("SQL_C_DEFAULT (99) should only be used for NULL parameters at index " + std::to_string(paramIndex));
+                        }
+                    }
+
+                    // For NULL parameters, we need to allocate a minimal buffer and set all indicators to SQL_NULL_DATA
+                    // Use SQL_C_CHAR as a safe default C type for NULL values
+                    char* nullBuffer = AllocateParamBufferArray<char>(tempBuffers, paramSetSize);
+                    strLenOrIndArray = AllocateParamBufferArray<SQLLEN>(tempBuffers, paramSetSize);
+
+                    for (size_t i = 0; i < paramSetSize; ++i) {
+                        nullBuffer[i] = 0;
+                        strLenOrIndArray[i] = SQL_NULL_DATA;
+                    }
+
+                    dataPtr = nullBuffer;
+                    bufferLength = 1;
+                    LOG("BindParameterArray: SQL_C_DEFAULT bound - param_index=%d, all_null=true", paramIndex);
+                    break;
+                }
                 default: {
                     LOG("BindParameterArray: Unsupported C type - "
                         "param_index=%d, C_type=%d",

tests/test_004_cursor.py

@@ -1598,6 +1598,38 @@ def test_executemany_empty_parameter_list(cursor, db_connection):
         db_connection.commit()
 
 
+def test_executemany_NONE_parameter_list(cursor, db_connection):
+    """Test executemany with an NONE parameter list."""
+    try:
+        cursor.execute("CREATE TABLE #pytest_empty_params (val VARCHAR(50))")
+        data = [(None,), (None,)]
+        cursor.executemany("INSERT INTO #pytest_empty_params VALUES (?)", data)
+        db_connection.commit()
+
+        cursor.execute("SELECT COUNT(*) FROM #pytest_empty_params")
+        count = cursor.fetchone()[0]
+        assert count == 2
+    finally:
+        cursor.execute("DROP TABLE IF EXISTS #pytest_empty_params")
+        db_connection.commit()
+
+
+def test_executemany_MIX_NONE_parameter_list(cursor, db_connection):
+    """Test executemany with an NONE parameter list."""
+    try:
+        cursor.execute("CREATE TABLE #pytest_empty_params (val VARCHAR(50))")
+        data = [(None,), ("Test",), (None,)]
+        cursor.executemany("INSERT INTO #pytest_empty_params VALUES (?)", data)
+        db_connection.commit()
+
+        cursor.execute("SELECT COUNT(*) FROM #pytest_empty_params")
+        count = cursor.fetchone()[0]
+        assert count == 3
+    finally:
+        cursor.execute("DROP TABLE IF EXISTS #pytest_empty_params")
+        db_connection.commit()
+
+
 def test_executemany_Decimal_list(cursor, db_connection):
     """Test executemany with an decimal parameter list."""
     try: