On Sat, 2007-09-01 at 11:58 +0800, RaghavendraK 70574 wrote:
> Hi,
>
> In one of the slides "http://www.sqlite.org/php2004/page-052.html";
> it is stated， "OR will make DBEngine not to use Indexes" and IN will
> make DBEngine use
> indexes"
>
> I could not understand the rationale abt this. Can u explain?
The point is (was) that if you have a table like this:
CREATE TABLE abc(a PRIMARY KEY, b, c);
Then the first query uses the index on a, the second does (did) not:
SELECT * FROM abc WHERE a IN ('hello', 'world');
SELECT * FROM abc WHERE a = 'hello' OR a = 'world';
However, since those slides were written SQLite has been updated so that
queries of the second form are internally transformed to the first, and
therefore may use an index.
Dan.
>
> regards
> ragha
>
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