或者至少我认为它们被称为子查询(新手和sqlite中的自我训练).我有来自同一数据库中两个表的两个SELECT语句.我想沿着列日期和符号加入这两个子查询.子查询分别工作正常,但是当我尝试JOIN时,我得到一个错误(语句中的错误：接近“JOIN”：语法错误).这是我的查询字符串：
SELECT date,symbol,SUM(oi*contract_settle) AS oi_dollar
FROM (SELECT date,oi,contract_settle
FROM ann
UNION
SELECT date,contract_settle
FROM qtr)
GROUP BY date,symbol
HAVING oi_dollar > 0
JOIN
(SELECT date,ret FROM crsp
USING (date,symbol))
谢谢！
解决方法
您的JOIN子句需要在GROUP BY子句之前.此外,我知道sqlite确实有一些不同的“可选”连接语法,但以下更标准的查询应该有效：
SELECT a.date,a.symbol,SUM(a.oi * a.contract_settle) AS oi_dollar
FROM (SELECT date,contract_settle
FROM ann
UNION
SELECT date,contract_settle
FROM qtr) a
INNER JOIN crsp c ON a.date = c.date AND a.symbol = c.symbol
WHERE a.oi * a.contract_settle > 0
GROUP BY a.date,a.symbol
如果您对oi和contract_settle列有更多了解(例如,它们永远不能都是负数),则a.oi<>的WHERE子句. 0和a.contract_settle<> 0可能会有更好的表现.
