"L B" <[EMAIL PROTECTED]> wrote in message news:[EMAIL PROTECTED] > Just to better understand, the index on (x,y,z), would > it be useful for queries like > > select * from table1 inner join table2 > on table1.x=table2.x and table1.y = table2.y and > table1.z=table2.z
Yes. > or > > "table1.y = table2.y and table1.z=table2.z" would not > benefit the index Correct. > (so it would be better 3 different > indexes) ... or a single index on (y, z) > because it is useful just for "field x" > comparison or to retrieve y and z values given x? ... or to retrieve z value given x and y. And also for various inequalities and sorts, e.g. select * from mytable where x between 100 and 200; select * from mytable where x=5 and y between 100 and 200; select * from mytable where x=5 and y=6 and z between 100 and 200; select * from mytable order by x; select * from mytable where x=5 order by y; select * from mytable where x=5 and y=6 order by z; Igor Tandetnik _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
