我有此数据：
+--------------------+-------------+------------------+
| timestamp | profit_loss | profit_loss_type |
+--------------------+-------------+------------------+
| lm58-1527906222477 | 0.00200000 | profit |
| lm58-1527906222477 | -0.00008617 | fraction |
| lm58-1527906222477 | -0.00027400 | normal |
| lm58-1527906222477 | 0.00008617 | nett |
| lm58-1527906222477 | 0.00027400 | nett |
| lm99-1527906222888 | 0.00200000 | profit |
| lm99-1527906222888 | -0.00008617 | fraction |
| lm99-1527906222888 | -0.00027400 | normal |
| lm11-1527906222999 | 0.00200000 | profit |
| lm11-1527906222999 | 0.00008617 | fraction |
| lm11-1527906222999 | 0.00027400 | normal |
+--------------------+-------------+------------------+
我想和timestamp一起获得profit_loss < 0，但没有profit_loss_type = 'nett'
所以我期望这样的结果：
+--------------------+
| timestamp |
+--------------------+
| lm99-1527906222888 |
+--------------------+
这是我的查询，以获取包含timestamp的所有profit_loss < 0：
SELECT timestamp
FROM gross_profit
WHERE profit_loss < 0
AND (profit_loss_type = 'normal' OR profit_loss_type = 'fraction')
GROUP BY timestamp
13367 rows in set (0.15 sec)
但是当我添加HAVING时，为什么结果不同？
SELECT timestamp
FROM gross_profit
GROUP BY timestamp
HAVING SUM(CASE WHEN profit_loss_type = 'nett' THEN 1 ELSE 0 END) = 0
AND SUM(CASE WHEN profit_loss < 0 THEN 1 ELSE 0 END) = 1;
10741 rows in set (0.23 sec)
在此模拟中，我只有1个包含profit_loss_type = nett的时间戳，因此结果应为13366。而不是10741。