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,ordORDER BY ord
这给我的结果类似于:
ord month count01 January 102 Febuary 103 march 305 May 407 July 208 August 209 September 211 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 研究外连接.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,ordORDER BY ord;@H_403_44@ 总结
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