在sqlite中使其变得简单
以下是我的squlite声明:在sqlite中使其变得简单,sqlite,Sqlite,以下是我的squlite声明: select code , case when (max(close)-min(close))/min(close)<0.1 then "grade1" when (max(close)-min(close))/min(close) <0.2 then "grade2" when (max(close)-min(close))/min(close) <0.3 then "grade3" else "grade4" end
select code ,
case when (max(close)-min(close))/min(close)<0.1 then "grade1"
when (max(close)-min(close))/min(close) <0.2 then "grade2"
when (max(close)-min(close))/min(close) <0.3 then "grade3"
else "grade4" end as type;
maxclose minclose/minclose使用了三次,如何使查询语句更简单?将计算放入子查询:
SELECT code,
CASE WHEN CloseRatio < 0.1 THEN 'grade1'
WHEN CloseRatio < 0.2 THEN 'grade2'
WHEN CloseRatio < 0.3 THEN 'grade3'
ELSE 'grade4'
END AS type
FROM (SELECT code,
(MAX(close) - MIN(close)) / MIN(close) AS CloseRatio
FROM MyTable);
可能有一种方法我不知道,但显而易见的方法是使用一个变量,不幸的是sqlite不支持这个变量。所以,我不确定是否有可能简化它。