I think this is an interesting question. Note the following:
count(col1) will tell you the number of non-null occurrences of col1
col1=value will return 1 is col1=value, 0 if col1<>value
1/0 will return null
thus,
count(1/(col1=value)) will tell you the number of occurences of value in
col1.
therefore, if you have three conditions on col1: value1, value2, value3, you
can run:
select count(1/(col1=value1)) C1, count(1/(col1=value2)) C2,
count(1/(col1=value3)) C3
from table where col1 in (value1,value2,value3);
does this help?
braxton
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Cindy
Sent: Thursday, April 26, 2001 4:02 PM
To: [EMAIL PROTECTED]
Subject: count(*) questions
OK, I have a perl script using mysql that pulls up a bunch of numbers
for a table. Problem is it's taking a long time because of the number of
select calls I'm making.
Basically, I have a sequence of calls of the form:
SELECT COUNT(*) FROM <table> WHERE <conditions>
(execute, get value of count, print out as cell item in table)
for each column in the row.
My question: Is there some way to consolidate all the calls in each
row into one select statment? Ie,
SELECT COUNT(*), COUNT(*), COUNT(*) FROM <table> WHERE <conditions#1>
<cond#2> <cond#3>
Then I'd do one call per row for a total of row queries, rather
than for rowXcolumns queries.
I'm thinking I might be able to do this with some form of aliasing,
but I'm kind of stumped on how to specify which set of conditions goes
to which count.
--Cindy
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