### Database Schema:
CREATE TABLE gasstations (
	GasStationID	INTEGER	NOT NULL	PRIMARY KEY,
	ChainID	INTEGER	NULL,
	Country	TEXT	NULL,
	Segment	TEXT	NULL
);

CREATE TABLE customers (
	CustomerID	INTEGER	NOT NULL	PRIMARY KEY,
	Segment	TEXT	NULL,
	Currency	TEXT	NULL
);

CREATE TABLE yearmonth (
	CustomerID	INTEGER	NOT NULL	PRIMARY KEY,
	Date	TEXT	NOT NULL	PRIMARY KEY,
	Consumption	REAL	NULL,
	foreign key (CustomerID) references customers (CustomerID)
);

CREATE TABLE products (
	ProductID	INTEGER	NOT NULL	PRIMARY KEY,
	Description	TEXT	NULL
);

CREATE TABLE transactions_1k (
	TransactionID	INTEGER	NULL	PRIMARY KEY,
	Date	DATE	NULL,
	Time	TEXT	NULL,
	CustomerID	INTEGER	NULL,
	CardID	INTEGER	NULL,
	GasStationID	INTEGER	NULL,
	ProductID	INTEGER	NULL,
	Amount	INTEGER	NULL,
	Price	REAL	NULL
);

### User's Query:
How much more was customer 7 consuming in April 2013 than customer 5?

### Extra Knowledge:
April 2013 refers to 201304 in the yearmonth.date
SELECT SUM(IIF(CustomerID = 7, Consumption, 0)) - SUM(IIF(CustomerID = 5, Consumption, 0)) FROM yearmonth WHERE Date = '201304'