Level Extreme platform
Subscription
Corporate profile
Products & Services
Support
Legal
Français
What to use instead of _tally for SUM() SQL Select?
Message
From
29/11/2005 09:13:23
 
General information
Forum:
Visual FoxPro
Category:
Databases,Tables, Views, Indexing and SQL syntax
Environment versions
Visual FoxPro:
VFP 9
Miscellaneous
Thread ID:
01072776
Message ID:
01072792
Views:
12
>>>>>The variable _tally indicates if SQL Select found any records. However, if the SQL Select has SUM() function _tally returns value of 1, even though there were no records matching WHERE.
>>>>>
>>>>>What do you recommend to use, instead of _tally, to check if SQL Select found records?
>>>>>
>>>>>Thank you.
>>>>
>>>>Add one column, count(1) as nTally.
>>>
>>>I will think about this, although, this may slow the query (maybe not significantly though). I found a solution, I think. The resulting value of SUM() function has NULL if no records match the WHERE clause.
>>>
>>>Thank you.
>>
>>Checking for .null. is the "correct" way, I did not read your message carefully. Anyway, adding "count(1) as ntally" will only make a marginal change to the select speed, if at all measurable.
>
>Thank you for confirming the "correct" approach.

This .null. value actually was introduced in VFP9, in earlier versions you had to use the count(1) solution.
Previous
Reply
Map
View

Click here to load this message in the networking platform