How to Search for a Null Value: Difference between revisions
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Or how to search for nothing. | Or how to search for nothing. | ||
It is not uncommon to want to search for records with a null value in a particular field. Which search string you use will depend on what it is that you don’t want to find. '''In EMu, the exclamation mark specifies NOT.''' Thus: | It is not uncommon to want to search for records with a null value in a particular field. Which search string you use will depend on what it is that you [[don’t]] want to find. '''In EMu, the exclamation mark specifies NOT.''' Thus: | ||
'''!+''' in an attachment field will return all records where there is no attachment in that field. | '''!+''' in an attachment field will return all records where there is no attachment in that field. | ||
Revision as of 16:50, 24 October 2022
Or how to search for nothing.
It is not uncommon to want to search for records with a null value in a particular field. Which search string you use will depend on what it is that you don’t want to find. In EMu, the exclamation mark specifies NOT. Thus:
!+ in an attachment field will return all records where there is no attachment in that field.
!* in any field will return records where there is no value in a field.
Keep in mind that these searches take longer than searches using complete words.
Example
Find all Lecythis specimens without images:
