// get layer
var layer : Layer = map.getLayers().getLayerByName("Cities");
var searchDef : SearchDef = new SearchDef();	

// select locations by the expression (see Appendix A)
searchDef.setExpression( "Capital = \"Y\"");
// specify the fields you want to retrieve (all fields by default)
searchDef.setFields( "Area Name, State, County");

// returns the Recodset object
var rs : Recordset = layer.search( searchDef);