CASE ​

CASE expression
WHEN value THEN result
[WHEN ...]
[ELSE result]
END

CASE
WHEN boolean condition THEN result
[WHEN ...]
[ELSE result]
END

select season_name, winners, 
case winners 
when 'Leicester City' then 'One win' 
when 'Blackburn Rovers' then 'One win' 
when '' then 'Unknown'
else 'Two or more wins' 
end 
from season
order by 1;

 season_name |      winners      |       case       
-------------+-------------------+------------------
 1992-1993   | Manchester United | Two or more wins
 1993-1994   | Manchester United | Two or more wins
 1994-1995   | Blackburn Rovers  | One win
 1995-1996   | Manchester United | Two or more wins
 1996-1997   | Manchester United | Two or more wins
 1997-1998   | Arsenal           | Two or more wins
 1998-1999   | Manchester United | Two or more wins
 1999-2000   | Manchester United | Two or more wins
 2000-2001   | Manchester United | Two or more wins
 2001-2002   | Arsenal           | Two or more wins
 2002-2003   | Manchester United | Two or more wins
 2003-2004   | Arsenal           | Two or more wins
 2004-2005   | Chelsea           | Two or more wins
 2005-2006   | Chelsea           | Two or more wins
 2006-2007   | Manchester United | Two or more wins
 2007-2008   | Manchester United | Two or more wins
 2008-2009   | Manchester United | Two or more wins
 2009-2010   | Chelsea           | Two or more wins
 2010-2011   | Manchester United | Two or more wins
 2011-2012   | Manchester City   | Two or more wins
 2012-2013   | Manchester United | Two or more wins
 2013-2014   | Manchester City   | Two or more wins
 2014-2015   | Chelsea           | Two or more wins
 2015-2016   | Leicester City    | One win
 2016-2017   |                   | Unknown
(25 rows)

select seasonid, htid, atid, case 
when ftscore='0-0' then 'Bore draw' 
when ftscore='1-1' then 'Score draw' 
when ftscore='2-2' then 'Score draw'
when ftscore='3-3' then 'Score draw'
when ftscore='4-4' then 'Score draw'
when ftscore='5-5' then 'Score draw'
else 'Not a draw'
end 
from match 
where seasonid=22 and htid=45
order by htid, atid;

 seasonid | htid | atid |    case    
----------+------+------+------------
      22 |   45 |   51 | Not a draw
      22 |   45 |   52 | Bore draw
      22 |   45 |   61 | Not a draw
      22 |   45 |   63 | Not a draw
      22 |   45 |   65 | Not a draw
      22 |   45 |   67 | Not a draw
      22 |   45 |   68 | Not a draw
      22 |   45 |   69 | Not a draw
      22 |   45 |   73 | Not a draw
      22 |   45 |   74 | Not a draw
      22 |   45 |   75 | Not a draw
      22 |   45 |   77 | Not a draw
      22 |   45 |   78 | Not a draw
      22 |   45 |   86 | Not a draw
      22 |   45 |   87 | Not a draw
      22 |   45 |   88 | Bore draw
      22 |   45 |   89 | Not a draw
      22 |   45 |   91 | Not a draw
      22 |   45 |   93 | Score draw
(19 rows)