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.
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