Why would you ever use count ('foo')?
I've looked at the difference between:
count(*) count(column_name) count(1)
For example: here: Count (*) vs Count (1) . Some respondents also state: count ('foo'). Why would you ever use count ('foo'). This seems to work:
select count('hello my name is joe bloggs and I finished school about ten years ago') from dbdisposals
Why would you need to pass a string to the count function?
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Using any literal value in count
has the same effect as count(*)
, it counts the number of rows in a group. Usage count('str')
has the same effect as count(1)
, i.e. Counts records where the value is not equal null
. Since there will be no literal value ( 'str'
or 1
) null
for any of the entries, it counts all entries.
The function count
counts all nonzero values, so literal value in count
has the same effect as count(*)
, but count(column_name)
only counts nonzero values in that column.
Using a string literal in count
works great, the only reason you avoid it is to be confusing.
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