'where a - b > 0' 与 'where a > b' 不一样吗

[c__sys]

在sqlite里，我的如下第二个查询失败了。不知道啥原因。

就是说这样写，可以：where endtime + duration - strftime('%s', CURRENT_TIMESTAMP) > 0

这样失败了：where endtime + duration > strftime('%s', CURRENT_TIMESTAMP)

====

sqlite> select planid, endtime, duration from plan where endtime + duration - strftime('%s', CURRENT_TIMESTAMP) > 0;
5|1334029971|486400
6|1335029971|586400
7|1336029971|686400
8|1337029971|786400
9|1338029971|886400
10|1339029971|986400
sqlite> select planid, endtime, duration from plan where endtime + duration > strftime('%s', CURRENT_TIMESTAMP);
sqlite>
sqlite> .exit

[rucypli]

不懂 应该是隐式转换的问题

[ACMAIN_CHM]

建议提供一些例子，这样方便测试。估计是数据类型转换的原因。

[c__sys]

thank you

sample data attached

$ cat plan.sql

DROP TABLE plan;
CREATE TABLE plan
(
PlanId integer PRIMARY KEY,
TaskId integer DEFAULT 0,
Cameraid varchar(64) DEFAULT '',
MediaCompressType integer DEFAULT 0,
MediaResolutionType integer DEFAULT 0,
Url varchar(256) DEFAULT '',
PlanType integer DEFAULT 0,
starttime integer DEFAULT 0,
endtime integer DEFAULT 0,
Duration integer DEFAULT 0,
AlarmSource varchar(256) DEFAULT '',
AlarmType varchar(256) DEFAULT '',
AlarmParm varchar(256) DEFAULT '',
Response integer DEFAULT 0
);

INSERT INTO plan VALUES ( 1, 0, "camera1", 0, 0, "url1", 60, 0, 1330029971, 86400, "alarm_source", "alarm_type", "alarm_param", 0 );
INSERT INTO plan VALUES ( 2, 0, "camera1", 0, 0, "url2", 60, 0, 1331029971, 186400, "alarm_source", "alarm_type", "alarm_param", 0 );
INSERT INTO plan VALUES ( 3, 0, "camera1", 0, 0, "url3", 60, 0, 1332029971, 286400, "alarm_source", "alarm_type", "alarm_param", 0 );
INSERT INTO plan VALUES ( 4, 0, "camera1", 0, 0, "url4", 60, 0, 1333029971, 386400, "alarm_source", "alarm_type", "alarm_param", 0 );
INSERT INTO plan VALUES ( 5, 0, "camera1", 0, 0, "url5", 60, 0, 1334029971, 486400, "alarm_source", "alarm_type", "alarm_param", 0 );
INSERT INTO plan VALUES ( 6, 0, "camera1", 0, 0, "url6", 60, 0, 1335029971, 586400, "alarm_source", "alarm_type", "alarm_param", 0 );
INSERT INTO plan VALUES ( 7, 0, "camera1", 0, 0, "url7", 60, 0, 1336029971, 686400, "alarm_source", "alarm_type", "alarm_param", 0 );
INSERT INTO plan VALUES ( 8, 0, "camera1", 0, 0, "url8", 60, 0, 1337029971, 786400, "alarm_source", "alarm_type", "alarm_param", 0 );
INSERT INTO plan VALUES ( 9, 0, "camera1", 0, 0, "url9", 60, 0, 1338029971, 886400, "alarm_source", "alarm_type", "alarm_param", 0 );
INSERT INTO plan VALUES ( 10, 0, "camera1", 0, 0, "url10", 60, 0, 1339029971, 986400, "alarm_source", "alarm_type", "alarm_param", 0 );

$

$ sqlite3 plan.db
sqlite> .read plan.sql
sqlite> .exit
$