Making != value use an index

[Anon]

I am trying to get this select command to use and index file - when I run explain i get a null value for the chosen key

Ihave been tryng alsorts regexp <>

this is the expression
Select * from categories where id != 'cfcd208495d565ef66e7dff9f98764da' and parent_id = 'cfcd208495d565ef66e7dff9f98764da' and showcategory = 'Y' order by categoryname

if i change the != to = the index is selected fine

can any one help or offer any suggestion.

[neuromancer]

Lets think about this, where "id != 'x'" will grab everything except a string 'x' so the index isn't going to help you find anything really.

Try the query like this

SELECT n,... FROM Categories WHERE parent_id = 'cfcd208495d565ef66e7dff9f98764da' AND showcategory = 'Y', id != 'cfcd208495d565ef66e7dff9f98764da'

I belive it will do the WHERE in order it is typed, so it will grab parent_id cfcd2... first, then in that result set find showcategory 'Y', then scan for != 'cfcd208495d565ef66e7dff9f98764da' (Which is all the remaining records, but much less to deal with)

This may not be true, need to read your database users manual and see how they work.