# Calculate Sql Server time difference in hours minutes and seconds

How to calculate a Sql Server time difference hours minutes and seconds with datediff ? The SQL Server function DATEDIFF() allows to calculate the difference between two timestamps, but only in one unit. For example, only seconds, or only minutes or only hours. This SQL Server script uses the datediff function and calculate in hours, minutes, and seconds.

So, calculating the difference between a start date and end date is not straightforward with SQL Server. This post shows you how to do so with a simple example query, explained step by step.

## How to calculate SQL Server time difference in hours, minutes and seconds ?

Therefore, as an example, this simple SQL query is using the DATEDIFF function with two timestamps having exactly one hour of difference. And every query gives only one unit

In other words, we must combine or concatenate several queries to get the hours, minutes, and seconds within one unique SQL query. Below each query is returning one unit.

#### SQL Server time difference with datediff in hours minutes and seconds

The queries below show:

• First, SQL Datediff in hours
• Then the SQL Datediff in minutes
• Last the SQL Datediff in seconds

However every time unit is not a time but only one single unit.

```-- Declare and initialize two variables with exactly one hour of difference: 9 - 8 = 1h
DECLARE @DateStart 	DATETIME
DECLARE @DateEnd 	DATETIME
SET @DateStart 	= '2017-03-10 08:00:00'
SET @DateEnd 	= '2017-03-10 09:00:00'

-- SQL Query returns difference in seconds : 3600 seconds
SELECT DATEDIFF(SECOND, @DateStart, @DateEnd) AS [Difference in Seconds]

-- SQL Query returns difference in minutes : 60 minutes
SELECT DATEDIFF(MINUTE, @DateStart, @DateEnd) AS [Difference in Minutes]

-- SQL Query returns difference in hours : 1 hour
SELECT DATEDIFF(HOUR, @DateStart, @DateEnd) AS [Difference in Hours]
```

Below are two different ways to calculate the time difference between two dates.

### 1. The first solution to get the difference between two timestamps in one single query

For instance, to get the difference in hours, minutes, and seconds, use this query, it works only if hours are smaller than 99.
Moreover, change the total in seconds in Hours, Minutes and Seconds, for example with 3 hours = 3600 * 3 = 14400.

```DECLARE @TimeInSeconds INT
SET 	@TimeInSeconds = 14400

SELECT
RIGHT('0' + CAST(@TimeInSeconds / 3600 AS VARCHAR),2) + ':' +
RIGHT('0' + CAST((@TimeInSeconds / 60) % 60 AS VARCHAR),2) + ':' +
RIGHT('0' + CAST(@TimeInSeconds % 60 AS VARCHAR),2)
```

### 2. The second solution is to calculate the time difference in hours minutes and seconds between two dates in one SQL Server query

Indeed, these SQL queries computes the time difference using first the seconds (multiplied by one hour in seconds is 60 * 60 = 3600. Then using the milliseconds (multiplied by one hour in milliseconds as 60 * 60 * 1000 = 3600 * 1000).

Certainly, it finally displays the result without the milliseconds using the CONVERT function and the data date format 108.

```-- Using the seconds as a base for conversion
select CONVERT(varchar, dateadd(s, 3 * 3600 , getdate()), 108) AS [Hours Minutes Seconds]

-- Using the milliseconds as a base for conversion
select CONVERT(varchar, dateadd(ms, 3 * 3600 * 1000, getdate()), 108) AS [Hours Minutes Seconds]
```

In this short post we have seen how to calculate a SQL Server datetime difference in hours, minutes, and seconds using the datediff function.

Here is the official Microsoft SQL Server documentation about the DATEADD() time function.

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How to calculate a time difference in hours with a SQL Server query ?

To calculate a time difference between datetime in hours, take the two date and times and do the difference by using the HOUR option combined with the DATEDIFF time function in SQL Server :
“SELECT DATEDIFF(HOUR, @DateStart, @DateEnd) AS [Difference in Hours]”

How to calculate a SQL time difference in minutes ?

To calculate a time difference between two dates in minutes, use the two date and times and calculate the difference with the MINUTE option of the T-SQL DATEDIFF function :
“SELECT DATEDIFF(MINUTE, @DateStart, @DateEnd) AS [Difference in Minutes]”

How to calculate time difference in seconds with SQL Server ?

In order to calculate the exact time difference between two timestamps to the seconds, do the difference using the SECOND option provided by the SQL Server database :
“SELECT DATEDIFF(SECOND, @DateStart, @DateEnd) AS [Difference in Seconds]”

How to calculate time difference in milliseconds with MS SQL ?

To calculate precisely the time difference in milliseconds, use the T-SQL built-in time function and the MILLISECOND keyword :
“SELECT DATEDIFF(MILLISECOND, @DateStart, @DateEnd) AS [Difference in Milliseconds]”

Likewise, to go further with T-SQL queries. Here is how to manage SQL Server text with more than 8000 characters within stored procedures.