问题
Hi, I am using the following query but it does not work,
SELECT strftime('%m',Since) AS Month FROM Dates
Type of Since column is DATETIME, but the result is shown an empty Month column without any error.
回答1:
strftime isn't broken, it just doesn't understand the format of the datestamps in your database.
SQLite version 3.7.9 2011-11-01 00:52:41
sqlite> create table dates (id int, d datetime);
sqlite> insert into dates (id,d) values (1, date('now'));
sqlite> insert into dates (id,d) values (2, 'bad date');
sqlite> insert into dates (id,d) values (3, NULL);
sqlite> insert into dates (id,d) values (4, datetime('now'));
sqlite> select * from dates;
1|2012-09-23
2|bad date
3|
4|2012-09-23 04:31:36
sqlite> select id, strftime('%m', d) from dates;
1|09
2|
3|
4|09
来源：https://stackoverflow.com/questions/12549671/strftime-function-in-sqlite-does-not-work