1

以下查询成功：

SELECT INTERVAL '00:00:00.000000' HOUR TO SECOND(6)
FROM DUAL;

以下失败：

SELECT INTERVAL time_field HOUR TO SECOND(6) -- time_field is a VARCHAR2(15)
FROM some_table;

带有以下错误：

ORA-00923: FROM keyword not found where expected

如何修复我的第二个查询以拉回 HOUR TO SECOND INTERVAL？

当我尝试：

SELECT cast(time_field AS INTERVAL HOUR TO SECOND(6))
FROM some_table

我得到以下信息：

ORA-00963: unsupported interval type

测试设置：

CREATE TABLE some_table (
   time_field VARCHAR2(50)
);

INSERT ALL
INTO some_table (time_field) VALUES ('10:00:00.000000')
INTO some_table (time_field) VALUES ('12:00:00.000000')
INTO some_table (time_field) VALUES ('15:00:00.000000')
INTO some_table (time_field) VALUES ('17:00:00.000000')
INTO some_table (time_field) VALUES ('20:00:00.000000')
INTO some_table (time_field) VALUES (NULL)
SELECT * FROM DUAL;
4

2 回答 2

0

您可以使用该TO_DSINTERVAL功能；此处使用 CTE 复制表的示例：

WITH some_table AS (SELECT '00:00:00.000000' AS time_field FROM dual)
SELECT TO_DSINTERVAL('0 ' || time_field)
FROM some_table;

TO_DSINTERVAL('0'||TIME_FIELD)
---------------------------------------------------------------------------
+000000000 00:00:00.000000000

请注意，要使函数能够识别格式，您必须提供“天”部分，因此需要添加虚拟'0 '字符串。

您的固定值查询返回的格式略有不同（或至少显示略有不同；间隔 daa 类型的格式模型与日期的方式完全相同，因此不确定如何准确表达）：

SELECT INTERVAL '00:00:00.000000' HOUR TO SECOND(6)
FROM DUAL;

INTERVAL'00:00:00.000000'HOURTOSECOND(6)
---------------------------------------------------------------------------
+00 00:00:00.000000

要复制它，cast如果需要，您可以这样做：

WITH some_table AS (SELECT '00:00:00.000000' AS time_field FROM dual)
SELECT CAST(TO_DSINTERVAL('0 ' || time_field) AS INTERVAL DAY TO SECOND(6))
FROM some_table;

CAST(TO_DSINTERVAL('0'||TIME_FIELD)ASINTERVALDAYTOSECOND(6))
---------------------------------------------------------------------------
+00 00:00:00.000000

... 要不就：

WITH some_table AS (SELECT '00:00:00.000000' AS time_field FROM dual)
SELECT CAST('0 ' || time_field AS INTERVAL DAY TO SECOND(6))
FROM some_table;

CAST('0'||TIME_FIELDASINTERVALDAYTOSECOND(6))
---------------------------------------------------------------------------
+00 00:00:00.000000

...这几乎是@catcall 首先建议的内容，但这也需要'0 '前置，否则你会得到一个ORA-01867. （或者，如果您尝试使用HOUR TO SECOND, ORA-00963，即使带有前置日期值）。但是，我猜（这只是一个猜测，虽然受过很少的教育）它正在做一个隐式TO_DSINTERVAL或类似的，我想我更喜欢使用一个显式的，所以我确定发生了什么。那可能只是我，虽然......

使用您的示例数据我也得到一个ORA-01867，但它是由 null 值引起的。您可以使用 acase在结果中将其保留为 null：

SELECT CASE WHEN time_field IS NULL THEN null
    ELSE CAST('0 ' || time_field AS INTERVAL DAY TO SECOND(6)) END
FROM some_table;

CASEWHENTIME_FIELDISNULLTHENNULLELSECAST('0'||TIME_FIELDASINTERVALDAYTOSECO
---------------------------------------------------------------------------
+00 10:00:00.000000
+00 12:00:00.000000
+00 15:00:00.000000
+00 17:00:00.000000
+00 20:00:00.000000


6 rows selected.
于 2012-09-11T22:33:35.793 回答
0

我认为需要这个（未经测试的）演员表。

SELECT cast (time_field as interval hour to second(6))
FROM some_table;

您的列必须是与强制转换为区间兼容的类型，并且它必须包含可以解释为区间的数据。

用于 CAST 的 Oracle 11g 文档

示例代码

create table test (
  interval_type interval day to second,
  varchar_type varchar2(35) 
);

insert into test values (
  (current_timestamp - to_date(current_date)),
  (current_timestamp - to_date(current_date))
);

select 
  interval_type, 
  varchar_type
from test;

INTERVAL_TYPE                                                                              VARCHAR_TYPE
{"Bytes":[-128,0,0,0,78,95,84,-102,-92,-83,-64],"ShareBytes":null,"Length":11,"Stream":{}} +000000000 18:35:24.000000

select 
  interval_type, 
  cast (varchar_type as interval day to second)
from test;

INTERVAL_TYPE                                                                               CAST(VARCHAR_TYPEASINTERVALDAYTOSECOND)
{"Bytes":[-128,0,0,0,78,95,84,-102,-92,-83,-64],"ShareBytes":null,"Length":11,"Stream":{}}  {"Bytes":[-128,0,0,0,78,95,84,-128,0,0,0],"ShareBytes":null,"Length":11,"Stream":{}}
于 2012-09-11T20:00:09.807 回答