Added controller with sql

modules/travel/back/methods/travel/getTravelDaysDuration.js

@@ -0,0 +1,44 @@
+
+const ParameterizedSQL = require('loopback-connector').ParameterizedSQL;
+module.exports = Self => {
+    Self.remoteMethod('getTravelDaysDuration', {
+        description: 'Return the total days of travel',
+        accessType: 'READ',
+        accepts: {
+            arg: 'id',
+            type: 'number',
+            required: true,
+            description: 'The travel id',
+            http: {source: 'path'}
+        },
+        returns: {
+            type: 'number',
+            root: true
+        },
+        http: {
+            path: `/:id/getTravelDaysDuration`,
+            verb: 'GET'
+        }
+    });
+
+    Self.getTravelDaysDuration = async id => {
+        let stmt;
+
+        stmt = new ParameterizedSQL(`
+        SELECT 
+            ROUND(
+                AVG(
+                    DATEDIFF(landed , shipped)
+                    )
+                )
+        FROM travel
+            WHERE agencyFk = ?
+                GROUP BY agencyFK`, [
+            id
+        ]);
+
+        let result = await Self.rawStmt(stmt);
+
+        return result;
+    };
+};