help! insert and replace via replace

Good day

Please help! I need replase and insert date with one SQL command..

I create table:
CREATE TABLE days (
user VARCHAR(8) NOT NULL,
date DATE NOT NULL,
count BIGINT UNSIGNED NOT NULL DEFAULT 0,
INDEX (user),
UNIQUE INDEX (date));

and I don't know how to change count field if date and user field not changed, but by(with) 1 equel command on insert and on replace...

command "replace days set count=count+1, user="test", date="2000-03-09";" add new record, but not change count field if run more times.
I try "replace days set count=(select 1+count from days where user="test" and date="2000-03-09");" -- not work.
No ideas URL
Please HELP!

p.s. sorry for bad english



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WBR,
/sancho