在CASE SQL语句中使用BETWEEN

Question

我想从我们的费率表中获得所有12个月的平均费率并将其除以数月,我开始用案例编写SQL选择,但我似乎在"之间"部分做错了.这是我的SQL

SELECT AVG(SELL_RATE),
       AVG(BUY_RATE),
       CASE MONTHS
            WHEN RATE_DATE( BETWEEN '2010-01-01' AND '2010-01-31') THEN 'JANUARY'
            ELSE 'NOTHING'
   END AS 'MONTHS'
FROM   RATE
WHERE  CURRENCY_ID = CURRENCY -033'

Answer 1

从你的案例中取出MONTHS,并删除括号......如下所示:

CASE 
    WHEN RATE_DATE BETWEEN '2010-01-01' AND '2010-01-31' THEN 'JANUARY'
    ELSE 'NOTHING'
END AS 'MONTHS'

你可以认为这相当于:

CASE TRUE
    WHEN RATE_DATE BETWEEN '2010-01-01' AND '2010-01-31' THEN 'JANUARY'
    ELSE 'NOTHING'
END AS 'MONTHS'