dhtmlxscheduler modifying sql query for OptionsConnector

I am facing a fundamental problem where in I want to retrieve only selected fields as options from database. It is not possible to achieve using “render_table” function.I am well aware of the fact that it can be done using “render_sql”. But when i tried it’s showing error.Could anyone please find a solution for it??

If you are using php, you can

Something like next

$grid->filter("fkId", 154); //WHERE fkId = 154