Creativity Within Structure

Triggers are SQL statements which are stored with the intention of being activated or fired when an event associated with a database table occurs. This could be any event including an INSERT, UPDATE and DELETE. Lets begin by creating a few simple insert triggers CREATE a trigger on the ORDERLINE table for the insert event. The trigger will update the corresponding PRODUCT record QTY_ORDERED by adding the value of QTY to QTY_ORDERED. CREATE TRIGGER tr_qty_ordered_value_insert ON Orderline FOR INSERT AS BEGIN UPDATE product SET QTY_ORDERED = QTY_ORDERED + ((SELECT qty from INSERTED) * (SELECT unitprice from INSERTED)) WHERE product.ProductID = (SELECT ProductID from INSERTED); END; Command(s) completed successfully. CREATE a trigger on the ORDERLINE table for the delete event. The trigger will update the corresponding PRODUCT record QTY_ORDERED by subtracting the value of QTY FROM QTY_ORDERED. CREATE TRIGGER tr_qty_ordered_value_delete ON Orde

Let's look into the ICMP protocol. Specifically, ping and traceroute. ICMP is the Internet Control Message Protocol and is a component of the IP Layer. Basically, used by hosts to communicate diagnostic network layer information that is carried in the IP payload. It communicates error messages which are acted on by the IP layer or the UDP or TCP protocols. All of the exercises were carried out using the open source network protocol analyzer "Wireshark". www.wireshark.org Describe in detail the protocols ARP and ICMP. ARP is the Address Resolution Protocol is similar to that of DNS. Where DNS resolves IP addresses to domain names, ARP resolves network layer IP addresses to link layer MAC addresses. In order to send a datagram the source must give the adaptor the IP address and the MAC address. For example, host A wants to send a packet to host B. Host A uses a cached ARP table to look up the IP address for any existing records of host B's MAC address. If the MA

What does it mean for a wireless network to be operating in "infrastructure mode?" Clients connected to a base station (an access point or router) are operating in infrastructure mode. They communicate indirectly through this access point or router which serves as a bridge to a wired network. Ad-hoc mode networks are networks that do not rely on a router or access point infrastructure. As a result, each client participates in the routing by forwarding data to the other connected clients. What are the differences between the following types of wireless channel impairments:  path loss, multipath propagation, interference from other sources? Multipath propagation is when packet loss occurs due to electromagnetic waves reflecting off of ground objects which then take paths of different lengths between sender and receiver. Interference from other sources happens when there is interference from radio sources transmitting in the same frequency band. Wireless phones and wirel