SQL/Sybase:SELECT ... GROUP BY ...没有？

Question

col1   col2
A      bear
A      dog
A      cat
B      bear
B      dog
B      cat
C      dog
C      cat
D      bear
D      dog
D      cat
E      bear
E      dog
E      cat
F      dog
F      cat

如果我想选择至少有一行的所有col1值col2 = 'bear',我可以这样做:

SELECT col1 
FROM mytable 
WHERE col1 IN ('A','B','C') 
GROUP BY col1 
HAVING col2 = 'bear'

这将返回A和B.

但我想只选择col1中没有行的值 col2 = 'bear'

我在想NOT HAVING,但这似乎不起作用.

有任何想法吗？谢谢!

Answer 1

SELECT m1.col1
     FROM mytable m1
     WHERE NOT EXISTS(SELECT NULL 
                          FROM mytable m2 
                          WHERE m2.col1 = m1.col1 
                              AND m2.col2 = 'bear')
         AND m1.col1 IN ('A', 'B', 'C')

Answer 2

你也可以使用这个技巧:

SELECT col1 
FROM mytable
WHERE col1 IN ('A','B','C') 
GROUP BY col1 
HAVING SUM(CASE col2 WHEN 'bear' THEN 1 ELSE 0 END)=0