SQL query to get current and last year sales - sql

Question

I have the following table Sales:
Date Store Sales
1/1/2015 St01 12123
1/1/2015 St02 3123
1/1/2016 St01 4213
1/1/2016 St03 2134
When I try to self join to get this year and last year sales the closed store is not showing up.
The result should be like this:
Date Store This year Sales Last Year Sales
1/1/2016 St01 4213 1212
1/1/2016 St02 0 3123
1/1/2016 St03 2134 0
My query as follows:
SELECT CY.DATE,
CY.store cy.Sales,
LY.sales
FROM sales CY,
sales LY
WHERE CY.store(+) = LY.store(+)
AND LY.DATE = CY.DATE - 365

Answer 1

Oracle Setup:
CREATE TABLE sales ( "DATE", Store, Sales ) AS
SELECT DATE '2015-01-01', 'St01', 12123 FROM DUAL UNION ALL
SELECT DATE '2015-01-01', 'St02', 3123 FROM DUAL UNION ALL
SELECT DATE '2016-01-01', 'St01', 4213 FROM DUAL UNION ALL
SELECT DATE '2016-01-01', 'St03', 2134 FROM DUAL;
Query:
SELECT TRUNC( SYSDATE, 'YY' ) AS "DATE",
Store,
SUM( CASE WHEN "DATE" = TRUNC( SYSDATE, 'YY' )
THEN sales END )
AS "This year sales",
SUM( CASE WHEN "DATE" = ADD_MONTHS( TRUNC( SYSDATE, 'YY' ), -12 )
THEN sales END )
AS "Last year sales"
FROM sales
GROUP BY store
ORDER BY store;
Output:
DATE STORE This year sales Last year sales
------------------- ----- --------------- ---------------
2016-01-01 00:00:00 St01 4213 12123
2016-01-01 00:00:00 St02 3123
2016-01-01 00:00:00 St03 2134

Answer 2

What you need is called Pivoting Table. Although Oracle has specific clauses to do it, you can use just plain and pure SQL to do so, like this:
SELECT store,
SUM(CASE WHEN Extract(year FROM DATE) = Extract(year FROM SYSDATE) THEN
sales
ELSE 0
END) AS "This year Sales",
SUM(CASE WHEN Extract(year FROM DATE) = Extract(year FROM SYSDATE) - 1 THEN
sales
ELSE 0
END) AS "Last year Sales"
FROM sales
WHERE Extract(year FROM DATE) >= Extract(year FROM SYSDATE) - 1
GROUP BY store
ORDER BY store
It would show:
Store This year Sales Last year Sales
St01 4213 12123
St02 0 3123
St03 2134 0
Note that makes no sense to have to column date as the first column. You couldn't group by it to show the output you want.
See the equivalent of this query here on fiddle: http://sqlfiddle.com/#!15/7662d8/6

Answer 3

Since I want the query to return day by day sales I used MT0 answer and added the dates, this way I can get the data for all year days.
WITH AllYear AS
(select to_date('2016-01-01', 'yyyy-mm-dd') + level - 1 AS dobs
from dual
connect by level <= 366)
SELECT dobs AS "DATE",
Store,
nvl(SUM(CASE
WHEN t.Date = dobs THEN
t.sales
END),
0) AS "This Year Sales",
nvl(SUM(CASE
WHEN t.Date = dobs-365 THEN
t.sales
END),
0) AS "Last Year Sales"
FROM Sales t,AllYear
where dobs='01-Jan-2016'
GROUP BY Store
ORDER BY Store;

Answer 4

The general solution is a full outer join, which includes all records from both joined tables. I don't know the Oracle syntax, but in MS SQL Server it would be something like this:
SELECT ISNULL(CY.DATE, LY.DATE) as DATE,
ISNULL(CY.store, LY.store) as STORE,
isnull(cy.Sales, 0),
isnull(LY.sales, 0)
FROM sales CY FULL OUTER JOIN sales LY
ON CY.store = LY.store
AND (CY.DATE IS NULL OR
DATEPART(year, LY.DATE) = DATEPART(year, CY.DATE) - 1
ISNULL(a, b) gives a if A IS NOT NULL, else b. DATEPART extracts specified part of a date; I'm comparing a difference of exactly one year rather than 365 days, in case "last year" is a leap year/

Answer 5

I only work with SQL Server. If anything is different, try to apply the same logic.
Declaring a temporary table to test the query:
DECLARE #Sales TABLE (
[Date] DATE,
Store NVARCHAR(10),
Sales INT
)
INSERT INTO #Sales VALUES
('1/1/2015','St01',12123),
('1/1/2015','St02',3123),
('1/1/2016','St01',4213),
('1/1/2016','St03',2134);
SELECT * FROM #Sales;
The actual query:
SELECT
CY_Date = CASE
WHEN CY.Date IS NULL THEN DATEADD(YEAR, 1, LY.Date)
ELSE CY.Date
END,
LY_Date = CASE
WHEN LY.Date IS NULL THEN DATEADD(YEAR, -1, CY.Date)
ELSE LY.Date
END,
Store = CASE
WHEN CY.Store IS NULL THEN LY.Store
ELSE CY.Store
END,
ISNULL(CY.Sales, 0) AS CY_Sales,
ISNULL(LY.Sales, 0) AS LY_Sales
FROM #Sales CY
FULL JOIN #Sales LY ON (CY.Store = LY.Store AND LY.Date = DATEADD(YEAR, -1, CY.Date))
WHERE (CY.Date = '1/1/2016' OR CY.Date IS NULL)
AND (LY.Date = DATEADD(YEAR, -1, '1/1/2016') OR LY.Date IS NULL);
Result:
CY_Date LY_Date Store CY_Sales LY_Sales
2016-01-01 2015-01-01 St01 4213 12123
2016-01-01 2015-01-01 St03 2134 0
2016-01-01 2015-01-01 St02 0 3123
How it works:
The FULL JOIN will will combine by the Store and the lines from the current and the year before.
The WHERE clause will filter by the current date '1/1/2016'. The NULLs are allowed because sometimes you don't have lines for the current or for the last year.
On the columns, CASES are used to create the dates if they are null (If the current date is null, get the last year + 1 year, and vice versa), to create the store if they are null and to place a zero instead of a null on the sales columns.