How to write this Trigger ?

From: <wy_at_fudan.edu>
Date: Wed, 03 Nov 1999 14:19:27 GMT
Message-ID: <7vpg9b$s8o$1@nnrp1.deja.com>

I have a table t1.
Create table t1(
CostName Char(10),
Cost Number(12,2) default 0,
AllCost Number(12,2) default 0
);
I Want to use Trigger to set AllCost = sum(Cost) by CostName. I use "after insert for each row" and get mutating error!

How to write this trigger!
or some better ways to realise this function.

eg:

Insert 'abc',1
the result 'abc',1,1
insert 'abc',2
the result 'abc',1,3


           'abc',2,3


insert 'abc',1
the result 'abc',1,4


           'abc',2,4


           'abc',1,4

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Before you buy. Received on Wed Nov 03 1999 - 08:19:27 CST