Database schema:

CREATE TABLE customers (
	"CustomerID" INTEGER NOT NULL -- example: ['5', '3'],
	"Segment" TEXT -- client segment, example: ['LAM', 'SME'],
	"Currency" TEXT -- example: ['CZK', 'EUR'],
	PRIMARY KEY ("CustomerID"), 
	UNIQUE ("CustomerID")
)


CREATE TABLE gasstations (
	"GasStationID" INTEGER NOT NULL -- Gas Station ID, example: ['45', '44'],
	"ChainID" INTEGER -- Chain ID, example: ['6', '13'],
	"Country" TEXT -- example: ['CZE', 'SVK'],
	"Segment" TEXT -- chain segment, example: ['Value for money', 'Premium'],
	PRIMARY KEY ("GasStationID"), 
	UNIQUE ("GasStationID")
)


CREATE TABLE products (
	"ProductID" INTEGER NOT NULL -- Product ID, example: ['2', '1'],
	"Description" TEXT -- example: ['Rucní zadání', 'Nafta'],
	PRIMARY KEY ("ProductID"), 
	UNIQUE ("ProductID")
)


CREATE TABLE transactions_1k (
	"TransactionID" INTEGER -- Transaction ID, example: ['2', '1'],
	"Date" DATE -- example: ['2012-08-24', '2012-08-23'],
	"Time" TEXT -- example: ['09:41:00', '10:03:00'],
	"CustomerID" INTEGER -- Customer ID, example: ['31543', '46707'],
	"CardID" INTEGER -- Card ID, example: ['486621', '550134'],
	"GasStationID" INTEGER -- Gas Station ID, example: ['3704', '656'],
	"ProductID" INTEGER -- Product ID, example: ['2', '23'],
	"Amount" INTEGER -- example: ['28', '18'],
	"Price" REAL -- example: ['672.64', '430.72'],
	PRIMARY KEY ("TransactionID")
)


CREATE TABLE yearmonth (
	"CustomerID" INTEGER NOT NULL -- Customer ID, example: ['39', '63'],
	"Date" TEXT NOT NULL -- example: ['201201', '201112'],
	"Consumption" REAL -- example: ['1598.28', '528.3'],
	PRIMARY KEY ("Date", "CustomerID"), 
	CONSTRAINT fk_yearmonth_customers FOREIGN KEY("CustomerID") REFERENCES customers ("CustomerID")
)

Question: Which of the three segments—SME, LAM and KAM—has the biggest and lowest percentage increases in consumption paid in EUR between 2012 and 2013?
Evidence: Increase or Decrease = consumption for 2013 - consumption for 2012; Percentage of Increase = (Increase or Decrease / consumption for 2013) * 100%; The first 4 strings of the Date values in the yearmonth table can represent year

SQL:
SELECT CAST((SUM(IIF(T1.Segment = 'SME' AND T2.Date LIKE '2013%', T2.Consumption, 0)) - SUM(IIF(T1.Segment = 'SME' AND T2.Date LIKE '2012%', T2.Consumption, 0))) AS FLOAT) * 100 / SUM(IIF(T1.Segment = 'SME' AND T2.Date LIKE '2012%', T2.Consumption, 0)), CAST(SUM(IIF(T1.Segment = 'LAM' AND T2.Date LIKE '2013%', T2.Consumption, 0)) - SUM(IIF(T1.Segment = 'LAM' AND T2.Date LIKE '2012%', T2.Consumption, 0)) AS FLOAT) * 100 / SUM(IIF(T1.Segment = 'LAM' AND T2.Date LIKE '2012%', T2.Consumption, 0)) , CAST(SUM(IIF(T1.Segment = 'KAM' AND T2.Date LIKE '2013%', T2.Consumption, 0)) - SUM(IIF(T1.Segment = 'KAM' AND T2.Date LIKE '2012%', T2.Consumption, 0)) AS FLOAT) * 100 / SUM(IIF(T1.Segment = 'KAM' AND T2.Date LIKE '2012%', T2.Consumption, 0)) FROM customers AS T1 INNER JOIN yearmonth AS T2 ON T1.CustomerID = T2.CustomerID