It's true yours will work, but with the PRIMARY KEY so will mine. And I
believe mine will be more efficient.
Both styles will cause a key lookup for all table2 entries and an INSERT
for any not found. As I understand REPLACE, your's will also cause a
DELETE and INSERT for any that are already in table3.
jim...
Christian Mack wrote:
>
> Jim Faucette wrote:
> >
> > Ed Williams wrote:
> > >
> > > I have two identical tables with one column
> > > all i want to do is merge them into one big table.
> > > and get rid of the duplicates at the same time...
> > > any ideas??
> > > oh yeah the column names are identical in both tables but this can be
> changed.
> > >
> >
> > CREATE table3 col_name same_def_as_others NOT NULL PRIMARY KEY;
> > INSERT INTO table3 SELECT DISTINCT col_name FROM table1;
> > INSERT INTO table3 SELECT DISTINCT col_name FROM table2;
> >
> > jim...
>
> Nope :)
> Because table1 could contain a row identical to one in table2 use this:
> CREATE table3 col_name same_def_as_others NOT NULL PRIMARY KEY;
> INSERT INTO table3 SELECT DISTINCT col_name FROM table1;
> REPLACE INTO table3 SELECT col_name FROM table2;
