Date and Time Functions

SQL Date and Time Functions are operations used to manipulate date and time values within SQL queries. They include functions DATEADD (adds a specified interval to a date), DATEDIFF (calculates the difference between two dates), and DATE_FORMAT (formats a date value according to a specified format). These functions assist in various tasks such as date arithmetic, extracting components from date/time values, and formatting dates for display or storage.

 

DATEADD: The SQL DATEADD function is used to add a specified interval to a date or datetime value.

Consider a table named Orders with the following columns: OrderID, OrderDate, and DeliveryDate. We want to calculate the delivery date by adding 3 days to the order date.

SELECT OrderID, OrderDate, DATEADD(day, 3, OrderDate) AS DeliveryDate FROM Orders;

In this example, the DATEADD function adds 3 days to the OrderDate for each order. The result set will include the OrderID, OrderDate, and the calculated DeliveryDate where each delivery date is three days ahead of the order date.

 

DATEDIFF: The SQL DATEDIFF function calculates the difference between two dates.

Consider a table named Employees with columns EmployeeID, HireDate, and TerminationDate. We want to calculate the tenure of each employee in days.

SELECT EmployeeID, HireDate, TerminationDate, DATEDIFF(day, HireDate, TerminationDate) AS TenureInDays FROM Employees;

In this example, the DATEDIFF function calculates the difference in days between the HireDate and TerminationDate for each employee. The result set will include the EmployeeID, HireDate, TerminationDate, and the calculated TenureInDays.

 

DATEPART: The SQL DATEPART function extracts a specific part (such as year, month, day, etc.) from a date or datetime value.

Consider a table named Orders with columns OrderID and OrderDate. We want to extract the year and month from the order date.

SELECT OrderID, OrderDate, DATEPART(year, OrderDate) AS OrderYear, DATEPART(month, OrderDate) AS OrderMonth FROM Orders;

In this example, the DATEPART function is used to extract the year and month from the OrderDate for each order. The result set will include the OrderID, OrderDate, OrderYear, and OrderMonth, where each row contains the year and month extracted from the order date.

 

DATE_FORMAT: The SQL DATE_FORMAT function formats a date value according to a specified format.

Consider a table named Sales with a column SalesDate storing dates. We want to display the sales dates in the format "YYYY-MM-DD".

SELECT DATE_FORMAT(SalesDate, '%Y-%m-%d') AS FormattedSalesDate FROM Sales;

In this example, the DATE_FORMAT function formats the SalesDate column according to the specified format '%Y-%m-%d', which represents the year, month, and day in the YYYY-MM-DD format. The result set will contain the FormattedSalesDate column with sales dates formatted accordingly.