What Data Type Does Datediff Return?
When working with dates and time in SQL, the DATEDIFF function is commonly used to calculate the difference between two dates. The result of the DATEDIFF function is an integer value representing the difference between the specified dates in terms of the specified date part.
The DATEDIFF function takes three parameters: the date part, the start date, and the end date. The date part specifies the unit of measurement for calculating the difference. Some commonly used date parts include:
- Year (yyyy): Calculates the number of years between two dates.
- Quarter (qq): Calculates the number of quarters between two dates.
- Month (mm): Calculates the number of months between two dates.
- Week (wk): Calculates the number of weeks between two dates.
- Day (dd): Calculates the number of days between two dates.
- Hour (hh): Calculates the number of hours between two dates.
- Minute (mi): Calculates the number of minutes between two dates.
- Second (ss): Calculates the number of seconds between two dates.
Data Type Returned by DATEDIFF
The data type returned by the DATEDIFF function depends on whether you are using SQL Server or MySQL:
In SQL Server:
The return type of DATEDIFF in SQL Server is INT. This means that the result will be an integer value.
The return type of DATEDIFF in MySQL is SIGNED INTEGER. This also means that the result will be an integer value, but it can be both positive and negative, depending on the order of the dates.
It’s important to note that if you want a more precise result, you can use other date functions like TIMESTAMPDIFF in MySQL, which returns a value with fractional parts.
Let’s see an example of using the DATEDIFF function to calculate the number of days between two dates in SQL Server:
DECLARE @StartDate DATE = ‘2021-01-01’;
DECLARE @EndDate DATE = ‘2021-01-31’;
SELECT DATEDIFF(DAY, @StartDate, @EndDate) AS DaysDiff;
This query will return the number of days between the start date ‘2021-01-01’ and end date ‘2021-01-31’ as an integer value. In this case, the result would be 30.
The DATEDIFF function is a useful tool for calculating date differences in SQL. It returns an integer value representing the difference between two dates based on the specified date part. The actual data type returned by DATEDIFF depends on the database management system being used.
- In SQL Server, DATEDIFF returns an INT data type.
- In MySQL, DATEDIFF returns a SIGNED INTEGER data type.
Understanding the return data type of DATEDIFF is important for performing calculations and handling the results appropriately in your SQL queries.