Managing Oracle Date Formats: All You Need to Know（oracle日期英文）

.

The Oracle database is one of the most widely used enterprise databases in the world. As such, it is critical that database administrators have a thorough understanding of how to manage Oracle date formats as they are a key part of any database’s architecture. This article will cover the basics of Oracle date formats and discuss how to manage and use them effectively.

Oracle dates are stored in an internal format, which is an 8-byte binary representation that represents the year, month and day of the date. The internal format is commonly referred to as Oracle’s Julian day format, and is based on the so-called Julian calendar, which is 365 days in length. Each day corresponds to an 8-byte Oracle date format of yyyyddd, with each yyyy corresponding to this year, and each ddd representing the Julian day of the year. Oracle’s Julian day format makes handling of dates for simple calculations simpler.

In order to store dates using Oracle’s Julian day format, you need to use the Oracle date function ‘TO_DATE’ with the appropriate date format mask. The TO_DATE function allows you to convert a character string, which represents a date, into an Oracle date format. You will need to provide a valid date format mask in the second parameter of the TO_DATE function, which enables you to specify the incoming character string and target Oracle date format. For example, the following statement will convert the string ‘20200615’, which represents ‘15 June 2020’ into Oracle’s Julian day format:

SELECT TO_DATE ('20200615', 'YYYYDDD') FROM DUAL;

The most commonly used Oracle date formats are DD-MON-YYYY, DD-MON-YY, DD-MON-RR, DD-MM-YYYY, DD-MM-YY and DD-MM-RR. Each of these formats can be used to store both U.S. and international dates. For example, the DD-MON-RR date format supports the U.K. date convention, which is dd/mm/yyyy. On the other hand, the DD-MM-YYYY format supports the ISO 8601 version of the date format, which is yyyy-mm-dd.

Once you have stored your dates in the Oracle Julian day format, you can also manipulate them with the help of the Oracle functions MONTHS_BETWEEN and ADD_MONTHS. These functions allow you to calculate the number of months or years between two dates, as well as adding a certain number of months or years to a date, respectively.

Finally, when it comes to handling date formats in Oracle, it’s important to be aware of the various time zones that can be used. Oracle supports multiple time zones, such as America/New_York, Europe/London and Asia/Kuala_Lumpur. You can use the FROM_TZ function to convert dates between different time zones.

In conclusion, managing Oracle date formats requires a thorough understanding of their internal representation, as well as their various formats. Furthermore, you should also be aware of the functions that can be used to manipulate and convert them, such as the TO_DATE and FROM_TZ functions. With a good understanding of Oracle date formats and their related functions, database administrators will be able to effectively manage and use them within Oracle databases.