Comparing two date fields in a SQL query

Posted on 2001-08-01
Last Modified: 2012-06-27

I'm using ADO in VB with an Access database.  I need to compare two date fields in a query to see how much time elapsed between the two dates.

In other parts of the program I am using the DateAdd function to do this.  In the query however I need something that I can use in SQL that will serve to provide the same functionality as DateAdd except in this case inside the query comparing whatever values are in the fields.


Question by:syntel
LVL 43

Expert Comment

ID: 6341066
dateadd is part of the vba function library so it should work in the same way within the query.

Author Comment

ID: 6341102

Are you sure that it will work with a *field name* which is NOT a variable name and serves a completely different purpose??

DateAdd("n", -SomeTime, FieldNameHere)

Author Comment

ID: 6341150
Just tried that. VB reports 'variable not defined'
Free Tool: Path Explorer

An intuitive utility to help find the CSS path to UI elements on a webpage. These paths are used frequently in a variety of front-end development and QA automation tasks.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.


Accepted Solution

dgorin earned 200 total points
ID: 6341269
This will return the difference between two date/time fields as a calculated column.  In this case, the difference is returned as the number of minutes, refer to the DATEDIFF documentation for other ways to use this function.

This may or may not be portable to all databases but will work fine with ADO to Access or SQL Server.

select StartDate, EndDate, DATEDIFF(n, StartDate, EndDate) as theDiff from ALERTS

Author Comment

ID: 6342176

Thanks for the tip.  I'm still trying to figure out how to use this function in the WHERE clause of a query.  I want the query to return records depending on how much time has elapsed since the date in field1 vs. field2.  So far I haven't found anything using the DATEDIFF in the WHERE part of the query and sadly I don't have my books here with me either.



Expert Comment

ID: 6342256
select *  from my_table  where (datefield2-datefield1) >10;

in this case it will return all records with date difference of more than 10 days. Didn't checked in help on how to define what category (minutes, months,...) to use for comparison, just used some "testing".
LVL 50

Expert Comment

by:Ryan Chong
ID: 6342958
Hi syntel,

N = 0

Select Count(Date1-Date2 > N) From Table


Author Comment

ID: 7106350
Sorry, didn't realize I left this open.

Featured Post

Free Tool: Postgres Monitoring System

A PHP and Perl based system to collect and display usage statistics from PostgreSQL databases.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Introduction While answering a recent question about filtering a custom class collection, I realized that this could be accomplished with very little code by using the ScriptControl (SC) library.  This article will introduce you to the SC library a…
When trying to find the cause of a problem in VBA or VB6 it's often valuable to know what procedures were executed prior to the error. You can use the Call Stack for that but it is often inadequate because it may show procedures you aren't intereste…
As developers, we are not limited to the functions provided by the VBA language. In addition, we can call the functions that are part of the Windows operating system. These functions are part of the Windows API (Application Programming Interface). U…
This lesson covers basic error handling code in Microsoft Excel using VBA. This is the first lesson in a 3-part series that uses code to loop through an Excel spreadsheet in VBA and then fix errors, taking advantage of error handling code. This l…

839 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question