SQL 和 ALL 运算符

Question

正在寻找一种优雅的方法来解决这个问题...

DECLARE @ZIP INT
SET @ZIP = 55555

IF @ZIP = ALL(SELECT ZIP FROM PEOPLE WHERE PERSONTYPE = 1) 
  PRINT 'All people of type 1 have the same zip!'
ELSE
  PRINT 'Not All people of type 1 have the same zip!'

问题是，如果 (SELECT ZIP FROM PEOPLE WHERE PERSONTYPE = 1) 没有返回任何记录，则上述 IF 的计算结果为 true。我正在寻找一种方法，当 ALL 的子查询没有返回记录时，使其计算结果为 false。

我当前的解决方案:

DECLARE @ZIP INT
SET @ZIP = 55555

DECLARE @ALLZIPS TABLE (INT ZIP)

INSERT INTO @ALLZIPS
SELECT ZIP FROM PEOPLE WHERE PERSONTYPE = 1

IF EXISTS(SELECT TOP 1 * FROM @ALLZIPS) AND (@ZIP = ALL (SELECT ZIP FROM @ALLZIPS))
  PRINT 'All people of type 1 have the same zip!'
ELSE
  PRINT 'Not All people of type 1 have the same zip!'

Answer 1

用途:

IF EXISTS(SELECT NULL
            FROM PEOPLE p
           WHERE p.persontype = 1
          HAVING MIN(p.zip) = @Zip
             AND MAX(p.zip) = @Zip) 
  PRINT 'All people of type 1 have the same zip!'
ELSE
  PRINT 'Not All people of type 1 have the same zip!'