Question

寻找一种优雅的解决方法......

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）没有返回记录，那么上面的IF计算结果为true。我正在寻找一种方法，当ALL的子查询没有返回任何记录时，将其评估为false。

我目前的解决方案：

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

使用：

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!'

Answer 2

考虑使用EXISTS。

IF @ZIP = ALL(SELECT ZIP FROM PEOPLE WHERE PERSONTYPE = 1)  
   AND EXISTS(SELECT 1 FROM PEOPLE WHERE PERSONTYPE = 1)

Answer 3

跳进去：

IF (SELECT SUM(CASE WHEN ZIP = @ZIP THEN 0 ELSE 1 END) 
    FROM PEOPLE WHERE PERSONTYPE = 1) = 0 
  PRINT 'All people of type 1 have the same zip!'
ELSE 
  PRINT 'Not All people of type 1 have the same zip!'

SQL和ALL运算符

3 个答案: