Migration

Migration.php

<?php

namespace Craft;

/**
 * The class name is the UTC timestamp in the format of mYYMMDD_HHMMSS_pluginHandle_migrationName.
 */
class m150904_071603_inspections_DistanceText extends BaseMigration
{
    /**
     * Any migration code in here is wrapped inside of a transaction.
     *
     * @return bool
     */
    public function safeUp()
    {
        // Get original field context
        $context = craft()->content->fieldContext;

        // Set supertable field context (there's only one supertable: 1)
        craft()->content->fieldContext = 'superTableBlockType:1';

        // Get distance field
        $field = craft()->fields->getFieldByHandle('distance');

        // Rename the field
        $field->name = 'Meters';

        // Save field
        craft()->fields->saveField($field);

        // Revert to original field context
        craft()->content->fieldContext = $context;

        return true;
    }
}