DATEDIFF() SQL Function

In Structured Query Language (SQL), DATEDIFF() is the function that is used to determine the difference between two dates or intervals. It is a powerful function provided by SQL to manage time and date.

This article will teach us about DATEDIFF() SQL function, its syntax, needs, and examples.

Syntax of DATEDIFF() function:

In the above syntax, 'interval' defines the unit of time for which you want to find the difference. The value of the interval can be day, month, year, minute, hour, second, week, etc. 'startDate' is the starting date or time. 'endDate' is the ending date or time.

List of interval values with their abbreviations:

Needs of DATEDIFF() function:

• The duration between events: It is used to calculate the duration between two events.
• Scheduling and planning: It is used to find out the time left to complete specific tasks.
• Age calculation: It helps to know the age of people based on their date of birth and current date.
• Academic duration: It helps to find the length of the academic course.
• Inventory management: It helps to trace the age or track the shelf life of the products.
• Expiry and renewal dates: It helps to find out the remaining time for expiry and renewal dates to manage warranty, license, etc.
• Travel duration: Travel websites use this function to calculate trip duration.
• Loan calculations: Banking systems use this function to find loan periods and interest rates on the basis of the loan start and end dates.
• Subscription services: It helps in handling the subscription services by calculating the remaining subscription time for the users.
• Project management: Project management tools help to find the task durations, project completion dates, etc.
• Employee leave management: HR systems use this function to track employee leave periods.

Examples of the DATEDIFF() function in Microsoft SQL Server:

We will understand the DATEDIFF() function properly with the help of examples.

Note: We will use the syntax in the context of Microsoft SQL Server. The syntax may differ from database to database.

Example 1:

Let us consider a table called 'Orders' with fields like orderId, orderDate, and deliveryDate.

Orders Table:

1. We will consider the above 'Orders' table and calculate the number of days between the orderDate and deliveryDate.

We will use the given statement to find the number of days:

We will use the given statement to find the number of years:

2. We will consider the above 'Orders' table and calculate the number of years between the orderDate and deliveryDate.

3. We will consider the above 'Orders' table and calculate the number of months between the orderDate and deliveryDate.

We will use the given statement to find the number of months:

Example 2:

Let us consider a table called 'Products' with fields like productId, productName, and releaseDate.

Products Table:

We will consider the above 'Products' table and calculate the number of months since releaseDate of the product.

We will use the given statement to find the number of months:

Let us consider a table called 'Employees' with fields like employeeId, Name, hireDate, and terminationDate.

Example 3:

Employees Table:

We will consider the above 'Employees' table and calculate the number of years worked by the employee.

We will use the given statement to find the number of years:

Example 4:

Let us consider a table called 'Meetings' with fields like meetingId, startTime, and endTime.

Meetings Table:

We will consider the above 'Meetings' table and calculate the duration of each meeting in minutes.

To find out how many minutes each meeting lasted, we will use the given statement:

Example 5:

Let us consider a table called 'Persons' which has fields like personId, Name, and birthDate.

Meetings Table:

We will consider the above 'Persons' table and calculate the age of each person in years.

We will use the given statement to find the age of each person:

Example 6:

Let us consider a table called 'Subscriptions' with fields like subscriptionId, startDate, and endDate.

Meetings Table:

We will consider the above'Subscriptions' table and calculate the duration of each subscription in weeks.

We will use the given statement to find the duration of each subscription:

Example 7:

Let us consider a table called 'Projects' with fields like projectId, startDate, and endDate.

Projects Table:

We will consider the above 'Projects' table and calculate the duration of each project in days.

We will use the given statement to find the duration of each project:

Example 8:

Let us consider a table called 'Logs', which has fields like logId, logTime, and previousLogTime.

Logs Table:

We will consider the above 'Logs' table and calculate the time difference in minutes between logTime, and previousLogTime.

We will use the given statement to find the time difference:

Example 9:

Let us consider a table called 'Users' with fields like userId, Name, and lastLoginDate.

Users Table:

We will consider the above 'Users' table and calculate the number of days since each user's last login.

We will use the given statement to find the number of days:

Example 10:

Let us consider a table called 'Sales' with fields like saleId, saleDate, and previous_quarter_end_date.

Sales Table:

We will consider the above 'Sales' table and calculate the number of quarters between the saleDate, and previous_quarter_end_date.

We will use the given statement to find the number of quarters:

Conclusion:

In this article, we have learned about the DATEDIFF() SQL function, which is used to find the difference between two intervals. We have acquired knowledge about the needs of this function. We have seen various examples to understand the usage of the DATEDIFF() SQL function in real-world scenarios, such as finding the age of people, calculating the difference between two dates or times, and many more.