Thanks to -sniff- for the awesome header image! You should post these to /r/learnsql instead. Note /r/SQL does not allow links to basic tutorials to be posted here. Please view the Wiki for online resources. Learning SQLĪ common question is how to learn SQL. SELECT count(a.field1), a.field2, SUM(b.field4) FROM a INNER JOIN b ON a.key1 = b.key1 WHERE a.field8 = 'test' GROUP by a.field1, a.field2 HAVING SUM(b.field4) > 5 ORDER by a.field.3įor those with SQL questions we recommend using SQLFiddle to provide a useful development and testing environment for those who wish to fully understand your problem and help devise a solution. Something as simple as line breaks and using reddit's built in code formatting (4 spaces at the start of each line) can turn this: This will greatly increase your chances of receiving the help you desire. If you are including actual code in a post or comment, please attempt to format it in a way that is readable for other users. We will gladly help where we can as long as you post the work you have already done or show that you have attempted to figure it out on your own. If you are a student or just looking for help on your code please do not just post your questions and expect the community to do all the work for you. While naturally we should endeavor to work as platform neutrally as possible many questions and answers require tailoring to the feature set of a specific platform. When requesting help or asking questions please prefix your title with the SQL variant/platform you are using within square brackets like so: In this tutorial, you have learned how to use the SQL DATEDIFF() function to calculate the difference between two dates.The goal of /r/SQL is to provide a place for interesting and informative SQL content and discussions. See the following example: SELECT DATEDIFF( '', '') It ignores all the time part of the date in the calculation. MySQL only returns the difference between two dates in days. Unlike SQL Server, MySQL has a slightly different DATEDIFF() function syntax: DATEDIFF(startdate,enddate) The following example shows how to use the DATEDIFF() function to calculate the year of services of employees up to January 1st, 2018: SELECT first_name,ĭATEDIFF( year, hire_date, '') year_of_servicesĬode language: SQL (Structured Query Language) ( sql ) DATEDIFF in MySQL In this case, it truncated the minute part and only consider the hour part. It also returns two because the DATEDIFF() function returns an integer only. The following example illustrates how to use the DATEDIFF() function to calculate the difference in hours between two DATETIME values: SELECT DATEDIFF( hour, ' 01:00:00', ' 03:00:00') Ĭonsider the following example: SELECT DATEDIFF( hour, ' 01:00:00', ' 03:45:00') As shown clearly in the result, because 2016 is the leap year, the difference in days between two dates is 2×365 + 366 = 1096. Notice that the DATEDIFF() function takes the leap year into account. To get the number of month or day, you change the first argument to month or day as shown below: SELECT DATEDIFF( month, '', ''), The following example returns the number of year between two dates: SELECT DATEDIFF( year, '', '') Ĭode language: SQL (Structured Query Language) ( sql ) The DATEDIFF() function returns an integer value with the unit specified by the datepart argument. The startdate and enddate are date literals or expressions from which you want to find the difference. The following table illustrates the valid parts of date in SQL Server: Valid Date Part The datepart is a part of the date in which you want the function to return. The following illustrates the syntax of the DATEDIFF() function in SQL Server: DATEDIFF ( datepart, startdate, enddate )Ĭode language: SQL (Structured Query Language) ( sql ) Arguments datepart To calculate the difference between two dates, you use the DATEDIFF()function. Summary: in this tutorial, you will learn how to use the SQL DATEDIFF() function to calculate the difference between two dates.
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