At 12:16 PM 7/21/2008, you wrote:
So just use REPLACE instead of INSERT...
Sure, but a Replace will delete the existing row and insert the new one
which means also maintaining the indexes. This will take much longer than
just updating the existing row. Now if there were only a couple of rows
then a Replace will work fine (but it would also execute Delete/Insert
triggers if I had any). But I have 50 million rows and will need to update
maybe 1/2% of those, all of those deletes and inserts will slow things down.
Now logically I thought this should work:
insert into Table2 select * from table1 on duplicate key update;
I thought if MySQL found a duplicate key on the insert, it would
automatically update the existing row that it found with the results from
table1 if I left out the column expressions in the update clause. But
apparently it doesn't work that way. It looks like I have to re-specify
each of the column names in Table1 in the Update clause as a column
assignment. I thought this was totally necessary because MySQL knew the
column assignments for the original insert, why couldn't it pick up where
it left off and use the existing row (specified by the duplicate key value
it found). Either that or just force me to specify the key value assignment
in the Update clause and not the whole column list which could be 100 columns.
Mike
<http://dev.mysql.com/doc/refman/5.0/en/replace.html>http://dev.mysql.com/doc/refman/5.0/en/replace.html
On Mon, Jul 21, 2008 at 11:44 AM, mos
<<mailto:[EMAIL PROTECTED]>[EMAIL PROTECTED]> wrote:
At 08:23 PM 7/20/2008, Perrin Harkins wrote:
On Sun, Jul 20, 2008 at 12:12 AM, mos
<<mailto:[EMAIL PROTECTED]>[EMAIL PROTECTED]> wrote:
> Is there a way to get "Insert ... select ... On Duplicate Update" to
update
> the row with the duplicate key?
That's what it does.
> Why can't it do this?
What makes you think it can't?
- Perrin
Perrin,
I can't specify all of the columns in a Set statement in the
OnDuplicate clause because I don't know what the column names are and
there could be 100 columns. I'd like to use something like:
insert into Table2 select * from table1 on duplicate key update;
but this gives me a syntax error.
Error Code : 1064
You have an error in your SQL syntax; check the manual that corresponds
to your MySQL server version for the right syntax to use near '' at line 1
So it is looking for an Update expression. I'd like it to update all the
columns in the Select statement to the row with the matching key. After
all, this is what the statement was trying to do in the first place. I
don't see why I have to explicitly specify all of the value assignments
in the On Duplicate phrase over again.
Mike
MySQL 5.0.24
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