SQLite has a date() function that enables you to return a date value based on a time string and any modifiers.
It returns the date in this format: YYYY-MM-DD
To use this function, you need to provide a time string, plus any (optional) modifiers. A modifier allows you to change the date, such as add a number of days, set it to local time, etc
Below is a list of valid time string formats that you can use in any date and time function in SQLite.
Below is a list of valid modifiers for date and time functions in SQLite.
In PostgreSQL you can use the EXTRACT() function to get the month from a date.
You can also use the DATE_PART() function to do the same thing.
You can use the following code examples in PostgreSQL if you have a month number but you want the month name instead.
In PostgreSQL, if you already have a month name, but you want to convert that name to the month number, you can do this with the EXTRACT() function.
If you’re familiar with PostgreSQL, you might know that you can use the EXTRACT() and the DATE_PART() functions to extract the month from a date. But those functions only allow you to extract the month number.
What if you need the month name?
You can get the month name from a date by using the TO_CHAR() function. This function returns a string based on the timestamp and the template pattern you provide as arguments.
This article provides a list of the standard date and time format strings that can be used when formatting dates and/or times using the FORMAT() function in SQL Server, along with examples using different cultures and data types.
These are the standard date and time format specifiers that are supported by the .NET Framework, and therefore, SQL Server. Each standard date and time format string is an alias for a custom date and time format string.
If you’re getting some really weird results when using the DATEDIFF() function in SQL Server, and you’re convinced the function contains a bug, don’t tear your hair out just yet. It’s probably not a bug.
There are scenarios where the results produced by this function can be pretty whacky. And if you don’t understand how the function actually works, the results will look completely wrong.
Hopefully this article can help clarify how the DATEDIFF() function is designed to work, and provide some example scenarios of where your results might not be as you’d expect.