diff --git a/week-1/mandatory/2-classes-db/task.md b/week-1/mandatory/2-classes-db/task.md
index 735de6ae..db460bd0 100644
--- a/week-1/mandatory/2-classes-db/task.md
+++ b/week-1/mandatory/2-classes-db/task.md
@@ -7,8 +7,28 @@ Below you will find a set of tasks for you to complete to consolidate and extend
 To submit this homework write the correct commands for each question here:
 
 ```sql
-
-
+--1
+select room_no from rooms where rate>100;
+--2
+select * from reservations where  (checkin_date  between '2020-09-01' and '2020-09-30')and ( checkout_date- checkin_date >3);
+--3
+select * from customers where city like 'M%';
+--4
+INSERT INTO room_types VALUES ('PENTHOUSE',185.00);
+--5
+INSERT INTO rooms   select 501 as room_no, def_rate,'PENTHOUSE' as room_type,null as no_guest from room_types where room_type='PENTHOUSE';
+
+INSERT INTO rooms   select 502 as room_no, def_rate,'PENTHOUSE' as room_type,null as no_guest from room_types where room_type='PENTHOUSE';
+--6
+INSERT INTO rooms VALUES (503,143.00,'PREMIER PLUS',null);
+--7
+select count(room_no) from reservations where  (checkin_date  between '2020-08-01' and '2020-08-31');
+--8
+select sum(checkout_date-checkin_date) from reservations where  (room_no  between 201 and 299);
+--9
+select count(res_id),sum(total),avg(total) from invoices where total >300;
+--10
+SELECT sum(checkout_date-checkin_date),floor(room_no/100)as floor_No from reservations group by floor(room_no/100) having floor(room_no/100)>0;
 ```
 
 When you have finished all of the questions - open a pull request with your answers to the `Databases-Homework` repository.
diff --git a/week-2/mandatory/2-ecommerce-db/task.md b/week-2/mandatory/2-ecommerce-db/task.md
index c48d2286..dfa7ab87 100644
--- a/week-2/mandatory/2-ecommerce-db/task.md
+++ b/week-2/mandatory/2-ecommerce-db/task.md
@@ -8,8 +8,32 @@ Below you will find a set of tasks for you to complete to set up a database for
 
 To submit this homework write the correct commands for each question here:
 ```sql
-
-
+--1
+select name,address from customers where country ='United States';
+--2
+select * from customers order by name;
+--3
+select * from products  where product_name like '%socks%';
+--4
+select p.* ,pa.unit_price,pa.supp_id from products p join product_availability pa on(p.id=pa.prod_id)  where pa.unit_price>100;
+--5
+select p.* from products p join product_availability pa on(p.id=pa.prod_id)  order by pa.unit_price desc limit 5;
+--6
+select p.product_name,pa.unit_price,s.supplier_name from products p join product_availability pa on(p.id=pa.prod_id)join suppliers s on (pa.supp_id=s.id) ;
+--7
+select p.product_name,s.supplier_name from products p join product_availability pa on(p.id=pa.prod_id)join suppliers s on (pa.supp_id=s.id) where s.country='United Kingdom' ;
+--8 
+ select o.id,o.order_reference,o.order_date,oi.quantity* pa.unit_price as total  from orders o  join order_items oi  on(o.id=oi.order_id) join product_availability pa on(oi.product_id=pa.prod_id) where o.customer_id=1 ;
+--9
+select o.*,oi.* from orders o  join order_items oi  on(o.id=oi.order_id) join customers c on(o.customer_id=c.id) where c.name='Hope Crosby' ; 
+--10
+select p.product_name,pa.unit_price,oi.quantity from product_availability pa join order_items oi  on(pa.prod_id=oi.product_id) join products p on(oi.product_id=p.id)join orders o on(o.id=oi.order_id) where o.order_reference='ORD006'and oi.supplier_id=pa.supp_id ;
+--11
+select c.name,o.order_reference,o.order_date, p.product_name,s.supplier_name,oi.quantity from orders o  join order_items oi  on(o.id=oi.order_id) join customers c on(o.customer_id=c.id)  join products p on(oi.product_id=p.id)join suppliers s on (oi.supplier_id=s.id) ;
+--12
+select distinct c.name from customers c join orders o on (o.customer_id=c.id)join order_items oi on(o.id=oi.order_id) join suppliers s on(s.id=oi.supplier_id) where s.country='China'
+--13
+select c.name,o.order_reference,o.order_date,sum(oi.quantity*pa.unit_price) as total_order from orders o  join order_items oi  on(o.id=oi.order_id) join customers c on(o.customer_id=c.id) join product_availability pa on(oi.product_id=pa.prod_id) group by o.id, c.name order by total_order desc;
 ```
 
 When you have finished all of the questions - open a pull request with your answers to the `Databases-Homework` repository.
diff --git a/week-2/mandatory/3-api/server.js b/week-2/mandatory/3-api/server.js
new file mode 100644
index 00000000..faceccda
--- /dev/null
+++ b/week-2/mandatory/3-api/server.js
@@ -0,0 +1,33 @@
+const express = require("express");
+const app = express();
+const { Pool } = require('pg');
+
+const pool = new Pool({
+    user: 'postgres',
+    host: 'localhost',
+    database: 'cyf_ecommerce',
+    password: 'allatif977A',
+    port: 5432
+});
+
+app.get("/customers", function(req, res) {
+    pool.query('SELECT * FROM customers', (error, result) => {
+        res.json(result.rows);
+    });
+});
+app.get("/suppliers", function(req, res) {
+    pool.query('SELECT * FROM suppliers', (error, result) => {
+        res.json(result.rows);
+    });
+});
+app.get("/products", function(req, res) {
+    pool.query('select p.product_name,pa.unit_price,s.supplier_name'+
+    ' from products p join product_availability pa on(p.id=pa.prod_id)'+
+    'join suppliers s on (pa.supp_id=s.id) ;', (error, result) => {
+        res.json(result.rows);
+    });
+});
+
+app.listen(3000, function() {
+    console.log("Server is listening on port 3000. Ready to accept requests!");
+});
\ No newline at end of file
diff --git a/week-3/server.js b/week-3/server.js
new file mode 100644
index 00000000..9afc4fe5
--- /dev/null
+++ b/week-3/server.js
@@ -0,0 +1,258 @@
+const express = require("express");
+const app = express();
+const { Pool } = require('pg');
+const bodyParser = require("body-parser");
+app.use(bodyParser.json());
+let supplierIdArr;
+let productIdArr;
+let customersIdArr;
+
+const pool = new Pool({
+    user: 'postgres',
+    host: 'localhost',
+    database: 'cyf_ecommerce',
+    password: 'allatif977A',
+    port: 5432
+});
+pool.query('SELECT * FROM suppliers', (error, result) => {
+    supplierIdArr= result.rows.map(r =>r.id);})
+
+    pool.query('SELECT * FROM products', (error, result) => {
+         productIdArr= result.rows.map(r =>r.id);})
+
+pool.query('SELECT * FROM customers', (error, result) => {
+            customersIdArr= result.rows.map(r =>r.id);})
+   
+app.get("/customers", function(req, res) {
+    pool.query('SELECT * FROM customers', (error, result) => {
+        res.json(result.rows);
+    });
+});
+
+app.get("/customers/by_name/:name", function(req, res) {
+    const cudtomerName=req.params.name.toLowerCase();
+    pool.query("SELECT * FROM customers where lower(name) like '%'||$1||'%'",[cudtomerName], (error, result) => {
+        res.json(result.rows);
+    });
+});
+
+app.post("/suppliers" ,function (req,res){
+    const newName=req.body.name;
+    const newCountry=req.body.country;
+
+    pool.query("SELECT 1 FROM suppliers WHERE supplier_name=$1", [newName],
+            (err, result) => {
+      if (result.rowCount > 0) {      // note the use of result.rowCount
+        return res
+          .status(400)
+          .send("A supplier with that name  already exists!");
+      } else {
+    pool.query("insert into suppliers (supplier_name,country )"+
+    "values($1,$2) returning id",[newName ,newCountry],(error,result)=> {
+        if ((error)== undefined){
+            //res.send("New customer added.");
+            //res.json(result.rows[0].id);
+            res.send("New supplier added.");
+        }
+        else {
+        res.status(400).send("wrong request "+error)
+    console.log(error);}
+    });
+}})
+});
+
+// delete order item
+app.delete("/order_items/:id" ,function (req,res){
+    const orderId=parseInt( req.params.id);
+
+    pool.query("delete from order_items  where  id=$1"
+ ,[orderId],(error)=> {
+        if ((error)== undefined){
+            
+            res.send("order_items "+orderId+" deleted.");
+        }
+    });
+});
+app.get("/suppliers", function(req, res) {
+    pool.query('SELECT * FROM suppliers', (error, result) => {
+        res.json(result.rows);
+    });
+});
+// app.get("/products", function(req, res) {
+//     pool.query('select p.product_name,pa.unit_price,s.supplier_name'+
+//     ' from products p join product_availability pa on(p.id=pa.prod_id)'+
+//     'join suppliers s on (pa.supp_id=s.id) ;', (error, result) => {
+//         res.json(result.rows);
+//     });
+// });
+
+
+//Homework
+
+//filter the list of products
+
+app.get("/products", function(req, res) {
+    const searchProduct = req.query.name;
+    console.log(searchProduct);
+    if (searchProduct!=undefined)
+    pool.query("select p.product_name,pa.unit_price,s.supplier_name"+
+    ' from products p join product_availability pa on(p.id=pa.prod_id)'+
+    "join suppliers s on (pa.supp_id=s.id) where lower(p.product_name) like '%'||$1||'%'",[searchProduct.toLowerCase()], (error, result) => {
+        res.json(result.rows);
+    })
+        else
+        pool.query('select p.product_name,pa.unit_price,s.supplier_name'+
+    ' from products p join product_availability pa on(p.id=pa.prod_id)'+
+    'join suppliers s on (pa.supp_id=s.id) ;', (error, result) => {
+        res.json(result.rows);
+    });
+
+    });
+    //new GET endpoint `/customers/:customerId`
+
+    app.get("/customers/:customerId", function(req, res) {
+        const cudtomerId=parseInt(req.params.customerId);
+        pool.query('SELECT * FROM customers where id =$1',[cudtomerId], (error, result) => {
+            res.json(result.rows[0]);
+        });
+    });
+//new POST endpoint `/customers`
+
+    app.post("/customers" ,function (req,res){
+        const newName=req.body.name;
+        const newCity=req.body.city;
+        const newAdd=req.body.address;
+        const newCountry=req.body.country;
+
+        pool.query("insert into customers (name,city ,address,country)"+
+        "values($1,$2,$3,$4) returning id",[newName ,newCity ,newAdd,newCountry],(error,result)=> {
+            if ((error)== undefined){
+                //res.send("New customer added.");
+                res.json(result.rows[0].id);
+                //res.send("New customer added.");
+            }
+            else {
+            res.status(400).send("wrong request "+error)
+}
+        });
+    });
+    
+    // new POST endpoint `/products`
+    app.post("/products" ,function (req,res){
+        const newName=req.body.name;
+
+        pool.query("insert into products (product_name)"+
+        "values($1) returning id",[newName ],(error,result)=> {
+            if ((error)== undefined){
+                //res.send("New customer added.");
+                res.json(result.rows[0].id);
+                //res.send("New customer added.");
+            }
+            else {
+            res.status(400).send("wrong request "+error)
+}
+        });
+    });
+    
+    //new POST endpoint `/availability`
+    app.post("/availability" ,function (req,res){
+        const productId=parseInt( req.body.productId);
+        const supplierId=parseInt(req.body.supplierId);
+        const price=parseInt(req.body.price);
+        if (price>0 && productIdArr.includes(productId) && supplierIdArr.includes(supplierId)){
+        pool.query("insert into product_availability "+
+        "values($1,$2,$3) ",[productId,supplierId,price ],(error,result)=> {
+            if ((error)== undefined){
+                res.send("New product_availability added.");
+               // res.json(result.rows[0]);
+                //res.send("New customer added.");
+            }
+            else {
+            res.status(400).send("wrong request "+error)
+}
+        });
+    }
+    else
+    res.status(400).send("the price must be positive and the id of the product and the suppliere must be existed  ")
+    });
+    
+
+    app.post("/customers/:customerId/orders" ,function (req,res){
+        const orderDate= req.body.orderDate;
+        const orderRef=req.body.orderRef;
+        const customerId=parseInt(req.params.customerId);
+        if (customersIdArr.includes(customerId) ){
+        pool.query("insert into orders (order_date,order_reference,customer_id) "+
+        "values($1,$2,$3) ",[orderDate,orderRef,customerId ],(error,result)=> {
+            if ((error)== undefined){
+                res.send("New order added.");
+               // res.json(result.rows[0]);
+                //res.send("New customer added.");
+            }
+            else {
+            res.status(400).send("wrong request "+error)
+}
+        });
+    }
+    else
+    res.status(400).send("The  id of the customer  must be existed  ")
+    });
+    
+
+    //PUT endpoint `/customers/:customerId`
+    app.put("/customers/:customerId" ,function (req,res){
+        const customerId=parseInt( req.params.customerId);
+        const newName=req.body.name;
+        const newCity=req.body.city;
+        const newAdd=req.body.address;
+        const newCountry=req.body.country;
+        if (customersIdArr.includes(customerId) ){
+                    pool.query("update customers set name=$1 ,city =$2,address=$3 ,country=$4"+
+        "where id =$5"
+     ,[newName,newCity ,newAdd,newCountry,customerId],(error)=> {
+            if ((error)== undefined){
+                
+                res.send("customer "+customerId+" updated.");
+            }
+        });
+    }else
+    res.status(400).send("This id "+customerId  +" is not  existed  ")
+    });
+
+    //Delete order
+    app.delete("/orders/:orderId" ,function (req,res){
+        const orderId=parseInt( req.params.orderId);
+    
+        pool.query("delete from order_items  where  order_id=$1"
+     ,[orderId],(error)=> {
+            if ((error)== undefined){
+                pool.query("delete from orders  where  id=$1"
+     ,[orderId],(error)=> {
+            if ((error)== undefined){
+                
+                res.send("order "+orderId+"  is deleted.");
+            }
+        });
+             
+            }
+        });
+        
+    });
+
+    //get all orders of specific customer
+    app.get("/customers/:customerId/orders", function(req, res) {
+        const cudtomerId=parseInt(req.params.customerId);
+        pool.query(' select o.order_reference,o.order_date,p.product_name,oi.quantity,s.supplier_name,pa.unit_price  '+
+        ' from orders o  join order_items oi  on(o.id=oi.order_id)'+
+        ' join product_availability pa on(oi.product_id=pa.prod_id and oi.supplier_id=pa.supp_id)'+
+        ' join products p  on(p.id=pa.prod_id)'+
+        ' join suppliers s on(s.id=pa.supp_id)'+
+
+        ' where o.customer_id=$1 ',[cudtomerId], (error, result) => {
+            res.json(result.rows);
+        });
+    });
+
+app.listen(3000, function() {
+    console.log("Server is listening on port 3000. Ready to accept requests!");
+});
\ No newline at end of file