sqlite – 如何填写缺少的月份？

SELECT STRFTIME('%m',date) ord,CASE STRFTIME('%m',date) WHEN '01' THEN 'January' 
                                   WHEN '02' THEN 'Febuary'
                                   WHEN '03' THEN 'March' 
                                   WHEN '04' THEN 'April' 
                                   WHEN '05' THEN 'May' 
                                   WHEN '06' THEN 'June' 
                                   WHEN '07' THEN 'July' 
                                   WHEN '08' THEN 'August' 
                                   WHEN '09' THEN 'September' 
                                   WHEN '10' THEN 'October' 
                                   WHEN '11' THEN 'November' 
                                   WHEN '12' THEN 'December' 
         ELSE '' END AS month,count(*) AS count 
    FROM events 
   WHERE type='Birth' AND 
         date <> '' 
GROUP BY month,ord
ORDER BY ord

这给我的结果类似于：

ord  month        count
01   January      1
02   Febuary      1
03   March        3
05   May          4
07   July         2
08   August       2
09   September    2
11   November     4

但正如你所看到的,它有差距.有没有办法用0计数来填补缺失的月份？

解决方法

运行以下一次：

CREATE TABLE months (
  mm char(2),name char(10)
);
INSERT INTO months VALUES ('01','January');
INSERT INTO months VALUES ('02','Febuary');
INSERT INTO months VALUES ('03','March');
INSERT INTO months VALUES ('04','April');
INSERT INTO months VALUES ('05','May');
INSERT INTO months VALUES ('06','June');
INSERT INTO months VALUES ('07','July');
INSERT INTO months VALUES ('08','August');
INSERT INTO months VALUES ('09','September');
INSERT INTO months VALUES ('10','October');
INSERT INTO months VALUES ('11','November');
INSERT INTO months VALUES ('12','December');

运行这个：

SELECT m.mm AS ord,m.name AS month,count(e.date) AS count
    FROM months m LEFT OUTER JOIN events e
      ON strftime('%m',e.date) = m.mm
   WHERE e.type='Birth' AND 
         e.date <> '' 
GROUP BY month,ord
ORDER BY ord;

（编辑：李大同）

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