Re: [SQL] comparing 2 tables. . .

On Fri, Sep 24, 1999 at 03:32:51PM +0100, Stuart Rison wrote:
...
> Try:
> 
> SELECT tab1.pkey FROM <your_table> tab1 WHERE tab1.pkey NOT IN (SELECT
> tab2.pkey FROM <your_other_table> tab2.pkey);
> 
> or else (faster):
> 
> SELECT tab1.pkey FROM <your_table> tab1 WHERE NOT EXISTS (SELECT 1 FROM
> <your_other_table> tab2 WHERE tab1.pkey=tab2.pkey);

Maybe this is trivial, but...

Is there a simple way to see that/why the last query is faster?

Albert.

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