如何在 SQL 中正确使用 case

阿卜杜勒·卡里姆汗 |

以下 SQL 代码出现小错误，我不明白其原因。

我正在使用 AWS Athena。

SELECT 
    icustay_id, 
    itemid, 
    date_diff('second', TIMESTAMP '1970-01-01 00:00:00', starttime) AS starttime, 
    date_diff('second', TIMESTAMP '1970-01-01 00:00:00', endtime) AS endtime,
    CASE WHEN itemid IN (30120,221906,30047) AND rateuom='mcg/kg/min' THEN CAST(rate AS DECIMAL(10,3))
FROM mimiciii.inputevents_mv
WHERE itemid IN (30128,30120,30051,221749,221906,30119,30047,30127,221289,222315,221662,30043,30307) 
ORDER BY icustay_id, itemid, starttime

以下是错误。

调用 StartQueryExecution 操作时发生错误 (InvalidRequestException)：第 2:1 行：外来输入 'case' 期望 {, ',', 'FROM', 'WHERE', 'GROUP', 'ORDER', 'HAVING', ' LIMIT', 'UNION', 'EXCEPT', 'INTERSECT'} 无法回滚

阿伦·帕拉尼萨米

Case 表达式的语法是：

CASE
WHEN boolean condition THEN result
[WHEN ...]
[ELSE result]
END

您END的 select 语句中缺少您。只需END在您的then条件后添加关键字，如下面的查询所示。它应该可以正常工作。

query_vaso_mv = """
select icustay_id, itemid, date_diff('second', timestamp '1970-01-01 00:00:00', starttime) as starttime, date_diff('second', timestamp '1970-01-01 00:00:00', endtime) as endtime,
case when itemid in (30120,221906,30047) and rateuom='mcg/kg/min' then cast(rate as DECIMAL(10,3)) end 
from mimiciii.inputevents_mv
where itemid in (30128,30120,30051,221749,221906,30119,30047,30127,221289,222315,221662,30043,30307) 
order by icustay_id, itemid, starttime
"""

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