Oracle program title: The winning team

The table nba records the name and year of the NBA (team VARCHAR2(10), y NUMBER(4)) winning team:

TEAM                   Y

-------------------------

Pistons 1990

Bull 1991

Bull 1992

Bull 1993

Rocket 1994

Rocket 1995

Bull 1996

Bull 1997

Bull 1998

Spurs 1999

Lakers 2000

Lakers 2001

Lakers 2002

Spurs 2003

Pistons 2004

Spurs 2005

Heat 2006

Spurs 2007

Celtic 2008

Lakers 2009

Lakers 2010

Please write an SQL statement to find out who has won the championship consecutively during this period, and what is the start and end time of the consecutive years,

The result is as follows:

TEAM                   B              E

------------------------------ ---------

Bull 1991 1993

Rocket 1994 1995

Bull 1996 1998

Lakers 2000 2002

Lakers 2009 2010

Answer:

SELECT MAX(nn.team) team,MIN(nn.y) Beginy,MAX(nn.y)+1 Endy
FROM	(SELECT n2.team,n2.y,ROWNUM,n2.y-ROWNUM
	 FROM (SELECT * FROM nba) n1  
	 INNER JOIN
	(SELECT * FROM nba) n2
         ON
	 n1.team=n2.team
	 WHERE
	 n1.y=n2.y+1) nn
GROUP BY (nn.y-ROWNUM)
ORDER BY Beginy;

1. Query the teams that have won awards for two consecutive years through their own query. For the convenience of understanding, two pseudo-columns are added to represent the row number and the year when the team started winning the award.

SELECT n2.team,n2.y,ROWNUM,n2.y-ROWNUM
FROM (SELECT * FROM nba) n1  
INNER JOIN (SELECT * FROM nba) n2
ON
n1.team=n2.team
WHERE
n1.y=n2.y+1

search result

2. Use the above results as a subquery, sort by the year of the award, and the last consecutive award year is MAX(nn.y)+1

SELECT MAX(nn.team) team,MIN(nn.y) Beginy,MAX(nn.y)+1 Endy
FROM	(SELECT n2.team,n2.y,ROWNUM,n2.y-ROWNUM
	 FROM (SELECT * FROM nba) n1  
	 INNER JOIN
	 (SELECT * FROM nba) n2
	 ON
	 n1.team=n2.team
	 WHERE
         n1.y=n2.y+1) nn
GROUP BY (nn.y-ROWNUM)
ORDER BY Beginy;

search result