Question

SELECT "Trade Details 2".Portfolio, 
       "Trade Details 2".CONTRACT_ID, 
       "Trade Details 2".START_DATE, 
       "Trade Details 2".MATURITY_DATE, 
       "Trade Details 2".NOTIONAL1,
       "Trade Details 2".CONTRACT_NPV,
       "Trade Details".TERM
FROM "Trade Details 2" 
JOIN "Trade Details" 
WHERE "Trade Details 2".CONTRACT_ID="Trade Details".FCC_ID and
      ("Trade Details 2".NOTIONAL1 > "0.0") and
      ("Trade Details 2".MATURITY_DATE > "20180621")

ORDER BY CONTRACT_ID asc

我正在尝试为我在此查询中加入的表中的START_DATE和MATURITY_DATE列固定日期格式。 START_DATE的格式类似于：2018-06-22 00:00:00，而MATURITY_DATE的格式类似于：20180622。我希望能够解决此问题，因此两列的格式相同，最好是2018-06-22。我已经在python中尝试过使用： input_string ='20191217'

start_date=pd.to_datetime(input_string[-2:]+input_string[4:6]+ 
input_string[:4], dayfirst=True)

但这没有用，只是声称语法无效。在SQL或Python中，有没有一种方法可以使这两列的日期相同？

Answer 1

您正在使用什么DBMS？例如，您需要使用STR_TO_DATE('your string', '%Y-%m-%d')来转换开始日期。

SELECT STR_TO_DATE('2018-06-22', '%Y-%m-%d') FROM DUAL;

Answer 2

编辑：更改了SQLite DB的查询

SELECT "Trade Details 2".Portfolio, 
       "Trade Details 2".CONTRACT_ID, 
       DATE("Trade Details 2".START_DATE) as START_DATE, 
       DATE(substr("Trade Details 2".MATURITY_DATE, 0, 5) || '-' || substr("Trade Details 2".MATURITY_DATE, 5,2) || '-' ||    substr("Trade Details 2".MATURITY_DATE, 7, 9)) as MATURITY_DATE, 
       "Trade Details 2".NOTIONAL1,
       "Trade Details 2".CONTRACT_NPV,
       "Trade Details".TERM
FROM "Trade Details 2" 
JOIN "Trade Details" 
WHERE "Trade Details 2".CONTRACT_ID="Trade Details".FCC_ID and
      ("Trade Details 2".NOTIONAL1 > "0.0") and
      ("Trade Details 2".MATURITY_DATE > DATE(substr('20180602', 0, 5) || '-' || substr('20180602', 5,2) || '-' ||    substr('20180602', 7, 9)) )

ORDER BY CONTRACT_ID asc

SQL中的固定日期格式

2 个答案: