Question

我想在Informix查询中添加过滤器：

WHERE agentstatedetail.eventdatetime < '1753-01-01 00:00:00' - INTERVAL(3) DAY TO DAY

但它失败了...... 请告诉它出错的地方。

Answer 1

如评论中所述，解决方案是确保将字符串解释为DATETIME值。这样做的简单方法是使用DATETIME文字符号：

DATETIME(1753-01-01 00:00:00) YEAR TO SECOND

演示：

CREATE TABLE agentstatedetail
(
    eventdatetime DATETIME YEAR TO SECOND NOT NULL PRIMARY KEY,
    eventname VARCHAR(64) NOT NULL
);

INSERT INTO agentstatedetail VALUES('1752-12-25 12:00:00', 'Christmas Day, Noon, 1752');
INSERT INTO agentstatedetail VALUES('1752-12-31 12:00:00', 'New Year''s Eve, Noon, 1752');
INSERT INTO agentstatedetail VALUES('1753-01-01 12:00:00', 'New Year''s Day, Noon, 1753');

SELECT * FROM agentstatedetail WHERE agentstatedetail.eventdatetime < '1753-01-01 00:00:00' - INTERVAL(3) DAY TO DAY;

这是嵌入最小SELECT语句的原始WHERE子句。它产生错误：

SQL -1261: Too many digits in the first field of datetime or interval.

（注意：在问题中包含错误信息会很有帮助。）

以下是查询的替代版本，其中包含DATETIME文字：

SELECT * FROM agentstatedetail
    WHERE agentstatedetail.eventdatetime < DATETIME(1753-01-01 00:00:00) YEAR TO SECOND -
                                           INTERVAL(3) DAY TO DAY
;

样本数据的输出：

1752-12-25 12:00:00|Christmas DAY, Noon, 1752

我观察到计算出的值是一个常数;你可以将代码重写为：

SELECT * FROM agentstatedetail
    WHERE agentstatedetail.eventdatetime < DATETIME(1752-12-29 00:00:00) YEAR TO SECOND

我怀疑该值是作为参数传递给该行的某个地方。

或者，您可以将字符串转换为DATETIME值，并获得相同的结果：

SELECT * FROM agentstatedetail
    WHERE agentstatedetail.eventdatetime < CAST('1753-01-01 00:00:00' AS DATETIME YEAR TO SECOND) -
                                           INTERVAL(3) DAY TO DAY
;

或：

SELECT * FROM agentstatedetail
    WHERE agentstatedetail.eventdatetime < '1753-01-01 00:00:00'::DATETIME YEAR TO SECOND -
                                           INTERVAL(3) DAY TO DAY

无法根据Informix中的日期过滤器过滤记录

1 个答案: