One of the date functions available in SQLite database is the julianday() function, which is used to convert a date and time value to a Julian day number.

The Julian day number is a continuous count of days and fractions of a day since noon Universal Time on January 1, 4713 BC (Julian calendar). The julianday() function in SQLite takes a date and time string in the format ‘YYYY-MM-DD HH:MM:SS’ or ‘YYYY-MM-DD’ and returns the corresponding Julian day number as a floating-point value.


Here is the syntax of the julianday() function in SQLite:

julianday(date_string, [modifier, modifier, ...])

The date_string parameter is a string value that represents the date and time in the format ‘YYYY-MM-DD HH:MM:SS’ or ‘YYYY-MM-DD’. The optional modifier parameters can be used to adjust the time zone offset, and to specify whether the input date and time values are in the Gregorian or Julian calendar.


Here is an example of using the julianday() function to convert a date and time string to a Julian day number:

SELECT julianday('2023-04-19 14:30:00');

The above query will return the Julian day number for April 19, 2023, at 2:30 PM as a floating-point value.

The julianday() function can be used in various scenarios, such as calculating the duration between two dates, sorting and filtering data by date and time, and performing date and time arithmetic.

In conclusion, the julianday() function in SQLite is a useful tool for converting date and time values to Julian day numbers, allowing for efficient calculations and manipulation of date and time data in SQLite databases.