Question

我的活动时间以YYYY-MM-DD HH：MM：SS的形式存储。

我要做的是找到事件的所有实例，它发生在前一个Trigger之后7个多小时。在阅读SQLite Date文档后，我不确定最简单的方法。我想我不得不以某种方式使用strftime，但我真的不确定如何处理它。

这是我必须建立的基本查询：

SELECT * FROM Event WHERE Event.DateTime (is more than 7 hours after) (SELECT Trigger.DateTime FROM Trigger WHERE Event.DateTime > Trigger.DateTime)

我目前设置的测试数据如下：

DROP TABLE IF EXISTS "Event";
CREATE TABLE "Event" ("DateTime" TEXT, "ID" INTEGER PRIMARY KEY  AUTOINCREMENT  NOT NULL  UNIQUE );
INSERT INTO "Event" VALUES('2000-01-01 08:00:00',1);
INSERT INTO "Event" VALUES('2000-01-01 09:00:00',2);
INSERT INTO "Event" VALUES('2000-01-01 14:00:00',3);
INSERT INTO "Event" VALUES('2000-01-01 15:00:00',4);
INSERT INTO "Event" VALUES('2000-01-01 20:00:00',5);
DROP TABLE IF EXISTS "Trigger";
CREATE TABLE "Trigger" ("DateTime" TEXT, "ID" INTEGER PRIMARY KEY  AUTOINCREMENT  NOT NULL  UNIQUE );
INSERT INTO "Trigger" VALUES('2000-01-01 00:00:01',1);
INSERT INTO "Trigger" VALUES('2000-01-01 10:00:01',2);

所以它应该从事件中返回1,2和5，因为那些是触发后超过7小时的事件。

Answer 1

是否有理由要针对Trigger.DateTime测试Event.DateTime两次？我认为这也应该有效：

SELECT * FROM Event 
WHERE EXISTS(SELECT 1 FROM Trigger 
             WHERE datetime(Event.DateTime,'+7 hours') > Trigger.DateTime)

<强>更新

由于您只想与最新的触发器进行比较，因此更像是这样：

SELECT * FROM Event 
WHERE EXISTS(SELECT MAX(Trigger.DateTime) newest FROM Trigger 
             HAVING datetime(Event.DateTime,'-7 hours') > newest)

修改

SELECT * FROM Event WHERE NOT EXISTS(SELECT 1 FROM Trigger WHERE datetime(Event.DateTime,'-7 hours') <= Trigger.DateTime) SELECT * FROM Event WHERE datetime(Event.DateTime,'-7 hours') > (SELECT MAX(Trigger.DateTime) newest FROM Trigger)

<强> EDIT2

SELECT * FROM Event WHERE NOT EXISTS(SELECT 1 FROM Trigger WHERE Trigger.DateTime BETWEEN datetime(Event.DateTime,'-7 hours') AND Event.DateTime) SELECT * FROM Event WHERE datetime(Event.DateTime,'-7 hours') > (SELECT MAX(Trigger.DateTime) newest FROM Trigger WHERE Trigger.DateTime < Event.DateTime)

Answer 2

怎么样

SELECT * FROM Event 
WHERE datetime(Event.DateTime,'+7 hours') > (SELECT Trigger.DateTime FROM Trigger 
                                           WHERE Event.DateTime > Trigger.DateTime)

如何在SQLite中使用特定长度比较时间？

2 个答案: