Here are two ways to convert a given Julian day to its date value in PostgreSQL.
The first method directly inputs the Julian day into the date data type.
The second method uses the to_date() function to return the same result.
Julian day is the number of days since Monday, January 1, 4713 BC using the proleptic Julian calendar, which is November 24, 4714 BC, in the proleptic Gregorian calendar.
Continue readingIn PostgreSQL, you can use the AT TIME ZONE clause to convert a timestamp to another timezone.
In PostgreSQL, the make_interval() function creates an interval from years, months, weeks, days, hours, minutes and seconds fields.
You provide the years, months, weeks, days, hours, minutes and/or seconds fields, and it will return an interval in the interval data type.
Continue readingIn PostgreSQL, the make_timestamptz() function allows you to create a timestamp with time zone from its year, month, day, hour, minute and seconds fields, as well as an optional timezone field.
In PostgreSQL, the make_date() function allows you to create a date from its separate year, month and day fields.
Each date part is provided as an integer, and the result is returned as a date.
Continue readingIn PostgreSQL, the make_time() function allows you to create a time from its hour, minute and seconds fields.
In PostgreSQL, the make_timestamp() function allows you to create a timestamp from its year, month, day, hour, minute and seconds fields.
In PostgreSQL, the statement_timestamp() function returns the current date and time (including the time zone offset), at the start of the current statement.
The function doesn’t accept any parameters, so you can’t specify its precision.
Also, statement_timestamp() is a non-SQL-standard function.
In PostgreSQL, the transaction_timestamp() function returns the current date and time (including the time zone offset), at the start of the current transaction.
It’s the equivalent of the traditional Postgres function now().
It’s also similar to the current_timestamp function (when called without an argument), except that it’s named to clearly reflect what it does.
The transaction_timestamp() function doesn’t accept any parameters, so you can’t specify its precision, whereas current_timestamp can be called with or without a precision parameter.
Also, transaction_timestamp() is a non-SQL-standard function.
In PostgreSQL, the now() function returns the current date and time (including the time zone offset), at the start of the current transaction.
It’s the equivalent of the transaction_timestamp() function.
It’s also similar to the current_timestamp function (when called without an argument).
The now() function doesn’t accept any parameters, so you can’t specify its precision, whereas current_timestamp can be called with or without a precision parameter.
Also, now() is non-SQL-standard (as is the transaction_timestamp() function).