My db has a column called status. This can take one of 7 or so integer values
from 0 to 7 or so. There are times when I need a quick answer to this question:
are there any rows in the db for which status has value 0. I don't need to know
how many, just whether there are any or not. What's the
On 11 Nov 2011, at 7:27pm, Tim Streater wrote:
select count(status) from mytable where status=0;
select count(status) from mytable where status=0 limit 1;
select status from mytable where status=0 limit 1;
When doing this a number of times I see some seconds of CPU being taken; I
select count(status) from mytable where status=0;
select count(status) from mytable where status=0 limit 1;
These two are identical because query always return one row thus
making limit 1 a no-op.
select status from mytable where status=0 limit 1;
This one will have the best performance
