将24小时的时间转换为12小时加AM / PM指示Oracle SQL [英] Convert 24 Hour time to 12 Hour plus AM/PM indication Oracle SQL

问题描述

我需要执行以下操作，我正在努力寻找解决方案：

I am required to do the following as an exercise, and I am struggling to find a solution:

编写一个SELECT语句，从发票表中返回这些列：

Write a SELECT statement that returns these columns from the Invoices table:

invoice_date列

The invoice_date column

使用TO_CHAR函数返回具有完整日期和时间的invoice_date列，包括24小时制四位数的年份

Use the TO_CHAR function to return the invoice_date column with its full date and time including a four-digit year on a 24-hour clock

使用TO_CHAR函数返回具有完整日期和时间的invoice_date列，其中包含一个四位数的年份一个12小时的时钟，一个am / pm指标。

Use the TO_CHAR function to return the invoice_date column with its full date and time including a four-digit year on a 12-hour clock with an am/pm indicator.

使用CAST函数将invoice_date列返回为VARCHAR2（10）

Use the CAST function to return the invoice_date column as VARCHAR2(10)

我可以得到的是：

    select invoice_date, to_char(invoice_date, 'DD-MM-YYYY HH:MM:SS') "Date 24Hr"
    from invoices

这是我的前两列，但是我无法确定任何方式来选择第三列。
任何帮助都会很棒，谢谢。 （是的，这是从我的学校教科书）

Which gets my first two columns, however I can't figure out any way to select the third column. Any help would be great, thanks. (And yes, this is from my school textbook)

推荐答案

对于24小时的时间，你需要使用 HH24 而不是 HH 。

For the 24-hour time, you need to use HH24 instead of HH.

对于12小时的时间， AM / PM指标写为 AM （如果您想要结果中的期间）或 AM （如果你't）。例如：

For the 12-hour time, the AM/PM indicator is written as A.M. (if you want periods in the result) or AM (if you don't). For example:

SELECT invoice_date,
       TO_CHAR(invoice_date, 'DD-MM-YYYY HH24:MI:SS') "Date 24Hr",
       TO_CHAR(invoice_date, 'DD-MM-YYYY HH:MI:SS AM') "Date 12Hr"
  FROM invoices
;

有关格式模型的更多信息，可以使用 TO_CHAR ，请参阅 http://docs.oracle.com /cd/E16655_01/server.121/e17750/ch4datetime.htm#NLSPG004 。

For more information on the format models you can use with TO_CHAR on a date, see http://docs.oracle.com/cd/E16655_01/server.121/e17750/ch4datetime.htm#NLSPG004.

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