On Tue, 10 Apr 2001, Peter Pentchev wrote:
> First, get a book on SQL. Read about joins in SELECT statements.
>
> Then, if you still need a quick answer, try the following:
>
> INSERT INTO table_c(name, score)
> SELECT name, a.score - b.score
> FROM table_a a
> LEFT JOIN table_b b ON b.name = a.name;
>
> Hope that helps.
I think this will give him problems with the values of table B that don't have a match
on table A, cause the expression number-NULL evaluates to NULL;
Maybe it would be better to:
CREATE TABLE C
SELECT A.name,IFNULL(A.score-B.score,A.score)
FROM A LEFT JOIN B ON A.name=B.name;
cheers,
thalis
>
> G'luck,
> Peter
>
> --
> No language can express every thought unambiguously, least of all this one.
>
> On Tue, Apr 10, 2001 at 03:57:54PM +0545, Deependra B. Tandukar wrote:
> > Greetings!
> >
> > I am using MySQL in RedHat 6.2 with PHP 4.0. I have a question on MySQL. Suppose I
>have two tables A and B in my database:
> > Table A
> > Name Score
> > a 45
> > b 20
> > c 75
> > d 55
> >
> > Table B
> > Name Score
> > a 20
> > b 9
> > c 25
> >
> > Now I need to subtract values of table B from table A and result should be
> > like:
> > Table C
> > Name Score
> > a 25
> > b 11
> > c 50
> > d 55
> >
> > How can I do this?
> >
> > Looking forward to hearing from you.
>
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