I tired to call the database in a HTML-Rule.
case "openCase" :
Database db = tools.getDatabase();
ClipboardPage lp = tools.createPage("Code-Pega-List", "");
var aSQL = "select TEST as \"TEST\" from Table where Field = 'ABC'"; var Result = db.executeRDB(aSQL, lp);
The public API is for JAVA not Java Script. calls to the public API only work in Java steps on activities, Rule Utility Functions, etc. I do not think you have access to the public API via Java Script.
Use a custom control alogn with scriptlets to do this.
Beaware, writing non-auto controls is not recommended by Pega