ArcGIS Javascript API Query

[AlexCarnes]

I have two polygon layers in a webmap service and want to do a dynamic query on click, such that when the user clicks on a lake (layer A) with ID = 100, the corresponding watershed boundary (layer B) with ID = 100 is highlighted. So basically, I want to pass the ID found on click from layer A and use that ID to query layer B by attribute. How do I do this?

[nicogis]

You can write js code like

on(dom.byId("execute"), "click", execute);
function execute (evt) {
        var aQuery = new esri.tasks.QueryTask("http://mymaps.com/arcgis/rest/services/myservice/MapService/0"); //layerA
        var aParams = new esri.tasks.Query();
        //...set your parameters
        aParams.geometry = evt.mapPoint;
        aQuery.execute(aParams, function (aResults) {
      
        var aQuery2 = esri.tasks.QueryTask("http://mymaps.com/arcgis/rest/services/myservice/MapService/1"); //layerB
        var aParams2 = new esri.tasks.Query();
        // ... set query parameters
        aParams2.where = "ID = " + aResults.features[0].attributes["ID"];
        aQuery2.execute(aParams2, function (aResults2) {
          //visualize in map
        
        });
      });
}

[AlexCarnes]

Thanks for your reply Domenico. I'm trying to use your example below with my published layers, and have yet to get it working. I think the issue is related to the visualize map section - I'm not too sure about how to handle that (I'm new to this)

on(dom.byId("execute"), "click", execute);  
  function execute (evt) {
  map.graphics.clear();
  var Symbol = new SimpleFillSymbol(SimpleFillSymbol.STYLE_SOLID,
                new SimpleLineSymbol(SimpleLineSymbol.STYLE_SOLID,
                  new Color([255, 0, 0]), 3), new Color([125, 125, 125, 0.35]));
        var aQuery = new esri.tasks.QueryTask("http://arcgis.geosyntec.com/arcgis/rest/services/BOS_MWBP/BOS_MWBP/MapServer/1"); //lakes
        var aParams = new esri.tasks.Query();  
        aParams.outFields = ["*"];
  aParams.returnGeometry = true;
        aParams.geometry = evt.mapPoint;  
        aQuery.execute(aParams, function (aResults) {  
        
        var aQuery2 = esri.tasks.QueryTask("http://arcgis.geosyntec.com/arcgis/rest/services/BOS_MWBP/BOS_MWBP/MapServer/2"); //layerB  
        var aParams2 = new esri.tasks.Query();  
  aParams2.outFields = ["*"];
  aParams2.returnGeometry = true;
        aParams2.where = "ID = " + aResults.features[0].attributes["ID"];  
        aQuery2.execute(aParams2, function (aResults2) { 
  graphic.setSymbol(Symbol);
  map.graphics.add(graphic);
           
        });  
      });  
}