When working with date data types in SQL, it is important to understand the default format in which dates are stored and displayed. The default format for date data type varies depending on the database management system (DBMS) being used. In this article, we will explore the default format for date data type in SQL.
Default Format for Date Data Type
In most DBMS, including MySQL, PostgreSQL, and Oracle, the default format for the date data type is YYYY-MM-DD. This means that dates are stored and displayed in a four-digit year, followed by a dash, followed by a two-digit month, another dash, and finally a two-digit day.
For example:
- 2021-01-15
- 1998-12-31
- 2005-07-10
This default format allows for easy sorting and comparison of dates. Since the year comes before the month and day, sorting dates in ascending or descending order will produce accurate results.
Date Functions and Conversion
Most DBMS provide various functions to manipulate and convert date values. These functions can be used to perform calculations on dates or change their display format.
For example, in MySQL:
- The
DATE_FORMAT()function allows you to customize the display format of a date value. - The
DATEDIFF()function calculates the number of days between two dates. - The
NOW()function returns the current date and time.
Similarly, other DBMS have their own set of date functions that can be used to manipulate and convert date data type as per your requirements.
Displaying Dates in Different Formats
If you prefer to display dates in a format different from the default, you can use the appropriate date formatting function provided by your DBMS. These functions allow you to customize the output format by specifying the desired pattern using special format codes.
For example, in MySQL:
SELECT DATE_FORMAT(date_column, '%d-%m-%Y') AS formatted_date FROM table;
This query will display the date in a day-month-year format like 15-01-2021. By changing the format pattern, you can display dates in various formats such as month-day-year or year-month-day.
Conclusion
In SQL, the default format for date data type is YYYY-MM-DD. This default format ensures consistency and allows for easy sorting and comparison of dates.
However, most DBMS provide functions that allow you to manipulate and convert dates as per your requirements. By using these functions, you can change the display format of dates or perform calculations on them. Remember to consult your DBMS documentation for specific syntax and available date functions.