Hi.
On Fri, Jul 06, 2001 at 03:45:48PM -0600, [EMAIL PROTECTED] wrote:
>
> to many hours anyway I am struggling with what seems to be an easy task but I am
>stuck.
>
> I am trying to total the fields with numbers (run + swim + bike) from a racer
>name="joe"
> and insert the ammount into a field called totals in a table called runner.
>
> UPDATE runner SET totals="SUM(run + swim + bike)" WHERE name="joe"
>
> Any hints
Start with the belonging SELECT:
mysql> SELECT "SUM(run + swim + bike)" FROM runner WHERE name="joe"
+------------------------+
| SUM(run + swim + bike) |
+------------------------+
| SUM(run + swim + bike) |
+------------------------+
which shows, that SUM() is not evaluated. How can this be? Because it
is a string. Everything within quotes is considered to be a string. So
drop these quotes.
The other thing is SUM() is a grouping function, i.e. it takes several
rows and sums up the expressions of all these rows. This is not what
you wish.
'+' works perfectly without any function around it. Just use
SELECT run + swim + bike FROM runner WHERE name="joe"
which should show the sum you want to write into 'totals'. Now the
UPDATE is an easy change:
UPDATE runner SET totals = run + swim + bike WHERE name="joe"
Starting with a belonging SELECT to the UPDATE one wants to perform is
always a good idea. It ensures that hte WHERE clause is correct, the
intended expression is correct and if you create the UPDATE from the
SELECT (with copy & paste or alike), you are safe of typos.
Bye,
Benjamin.
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