如何将两个sqlite语句合并为一个语句？

Question

 create  table  tmp  as select code,avg(how-low)/low  as vol  from quote group by code;
 select  avg(vol) from tmp

我用第一个语句创建一个新表，然后从tmp table中选择ave（vol）。如何将两个sqlite语句组合成一个语句？

Answer 1

如果您以后不需要临时表，请使用common table expression：

WITH tmp AS (SELECT avg(how-low)/low AS vol
             FROM quote
             GROUP BY code)
SELECT avg(vol)
FROM tmp

如果你有一个过时的SQLite版本（早于3.8.3），你可以使用子查询：

SELECT avg(vol)
FROM (SELECT avg(how-low)/low AS vol
      FROM quote
      GROUP BY code)