Mine

this.queryText = "SELECT * FROM opportunities INNER JOIN opportunities_cstm ON (opportunities.id = opportunities_cstm.id_c) INNER JOIN users ON (opportunities.assigned_user_id = users.id) WHERE opportunities.id > 0";

if(params["probOperator"].value != "" || params["probOperator"].value != null) { 
	this.queryText += " and opportunities.probability " + params["probOperator"] + " " + params["probability"];
}