SQL: I have this tables below I want to find;

The most active seller (the one who has offered the most number of items)

The most active buyer (the one who has bought the most number of items)

The most popular seller (the one who sold the most number of items)

The most expensive item sold ever

The most expensive item available

The cheapest item sold ever

The cheapest item available

create table creditCardInfo

( credit_CardID int IDENTITY(1000,1) NOT NULL, credit_CardNo varchar(16) UNIQUE NOT NULL, credit_ExptDate date NOT NULL, credit_OwnerName varchar(20) NOT NULL, PRIMARY KEY(credit_CardID));

create table Address ( addressID int IDENTITY(1000,1) NOT NULL, Street varchar(50) NOT NULL, City varchar(20) NOT NULL, State char(2) NOT NULL, ZIP char(10) NOT NULL,

primary key (addressID));

create table contactInfo ( contactID int IDENTITY (100,1) NOT NULL, telephone char(10) NOT NULL UNIQUE, Email varchar(50) NOT NULL UNIQUE, address_ID int ,

PRIMARY KEY(contactID), FOREIGN KEY (address_ID) references Address(addressID));

create table seller ( sellerID INT IDENTITY(1000,1) NOT NULL, sellerName varchar(20) NOT NULL, sellerUserName varchar(20) UNIQUE, sellerPassword varchar(32) NOT NULL,

item_ID int NOT NULL, contact_ID int NOT NULL, creditCardID int NOT NULL, primary key(sellerID),

Foreign Key(contact_ID) references contactInfo(contactID), Foreign Key(creditCardID) references creditCardInfo(credit_CardID));

create table item

( itemID int IDENTITY(1000,1) NOT NULL, itemName varchar(15) NOT NULL, Item_desc varchar(255), Item_initialPrice MONEY, ItemQty int, ownerID int NOT NULL, condition varchar(20) NOT NULL,

PRIMARY KEY (itemID),

FOREIGN KEY (ownerID) references seller (sellerID));

create table buyer

( buyerID INT IDENTITY(1000,1) NOT NULL, buyerName varchar(20) NOT NULL, buyerUsername varchar(20) UNIQUE NOT NULL, buyerPassowrd varchar(32) NOT NULL,

contact_ID int, creditCardID int,

primary key(buyerID),

Foreign Key(contact_ID) references contactInfo(contactID), Foreign Key(creditCardID) references creditCardInfo(credit_CardID));

create table buyerItem ( buyer_ID int NOT NULL, item_ID int NOT NULL, PRIMARY KEY(buyer_ID,item_ID),

FOREIGN KEY (buyer_ID) REFERENCES buyer(buyerID), FOREIGN KEY (item_ID) REFERENCES item(itemID));

create table picture

( pictureID int IDENTITY (1,1) NOT NULL, pictureIMG VarBinary(max), item_ID int,

PRIMARY KEY(pictureID), FOREIGN KEY(item_ID) references item(itemID));

create table bid

( bidID int IDENTITY (1000,1) NOT NULL, bid_startTime date DEFAULT GETDATE()NOT NULL, bid_endTime date DEFAULT GETDATE()NOT NULL, item_ID int NOT NULL,

PRIMARY KEY(bidID),

Foreign Key(item_ID) references item(itemID));

create table buyerBid

( buyer_ID int NOT NULL, bid_ID int NOT NULL, PRIMARY KEY(buyer_ID,bid_ID), FOREIGN KEY (buyer_ID) REFERENCES buyer(buyerID), FOREIGN KEY (bid_ID) REFERENCES bid(bidID));