oracle能单独存一个不带时间的日期么？或者是不带日期的时间

Posted 2023-03-21

貌似总是有时间

不行，oracle没有不带时间的日期，oracle日期时间类型有date和timestamp，都带日期和时间，文档中说：
DATE
Valid date range from January 1, 4712 BC, to December 31, 9999 AD. The default format is determined explicitly by the NLS_DATE_FORMATparameter or implicitly by the NLS_TERRITORY parameter. The size is fixed at 7 bytes. This datatype contains the datetime fields YEAR, MONTH, DAY,HOUR, MINUTE, and SECOND. It does not have fractional seconds or a time zone.

TIMESTAMP [(fractional_seconds_precision)] 参考技术A 不行，oracle没有不带时间的日期，oracle日期时间类型有date和timestamp，都带日期和时间，文档中说：
DATE
Valid date range from January 1, 4712 BC, to December 31, 9999 AD. The default format is determined explicitly by the NLS_DATE_FORMATparameter or implicitly by the NLS_TERRITORY parameter. The size is fixed at 7 bytes. This datatype contains the datetime fields YEAR, MONTH, DAY,HOUR, MINUTE, and SECOND. It does not have fractional seconds or a time zone.

TIMESTAMP [(fractional_seconds_precision)]
Year, month, and day values of date, as well as hour, minute, and second values of time, where fractional_seconds_precision is the number of digits in the fractional part of the SECOND datetime field. Accepted values of fractional_seconds_precision are 0 to 9. The default is 6. The default format is determined explicitly by the NLS_DATE_FORMAT parameter or implicitly by the NLS_TERRITORY parameter. The sizes varies from 7 to 11 bytes, depending on the precision. This datatype contains the datetime fields YEAR, MONTH, DAY, HOUR, MINUTE, and SECOND. It contains fractional seconds but does not have a time zone.

如果确实不想带时间，可以考虑用number(8,0)，这比varchar(8)或varchar(10)查询效率高追问

这个问题明白了
再问个问题：
就是如果对应java的float和double，我是不用number比用float好？
那我number的那两个参数怎么定义呢？

追答

oracle里有binary_float与binary_double，但印象中这2个jdbc不能访问，而且数据库数据一般都要求精确，所以我一般很少用浮点类型的，都是用数值类型，对应到java就是BigDecimal

本回答被提问者和网友采纳 参考技术B 不行 存储在数据表里会自动加上时分秒的
一般也不会有这样的要求 如果一定要这样做 就把数据类型改为字符串即可
--转换如下
selec to_char(字段,'yyyy-mm-dd') from 表名 参考技术C 只是显示格式的问题，to_char一下就可以了。你用的是timestamp类型？ 参考技术D 可以修改DATE的类型或者直接修改为VARCHAR2类型，指定为自己想要的字段类型，但已经定义好的字面，不能再修改啦．