sql - Would it be better to rewrite this query using EXISTS instead of IN? How would I do that? -

sql - Would it be better to rewrite this query using EXISTS instead of IN? How would I do that? -

i have following, , i've read it's improve avoid "in" , utilize "exists" instead (1, 2). though i've read exists faster , more consistent, don't think i've grasped exclusively why is, or how go rewriting utilize exists instead.

select qryaccountnamesconcat.accountid, qryaccountnamesconcat.accountname, qryaccountnamesconcat.jobtitle qryaccountnamesconcat (((qryaccountnamesconcat.accountid) in ( select accountid tblaccount accounttypeid in (1, 2)) or qryaccountnamesconcat.accountid in ( select childaccountid qryaccjunctiondetails parentaccounttypeid in (1, 2)) ));

basically, accounttypeid = 1 or 2 trade or private client account, looking accounts are, or children of (usually employees of) client accounts.

i not know if exists improve in ms access (although exists performs improve in in other databases). however, write as:

select anc.accountid, anc.accountname, anc.jobtitle qryaccountnamesconcat anc exists (select 1 tblaccount a.accounttypeid in (1, 2) , anc.accountid = a.accountid ) or exists (select 1 qryaccjunctiondetails jd jd.parentaccounttypeid in (1, 2) , jd.childaccountid = anc.accountid );

for best performance, want index on tblaccount(accountid, accounttypeid) , qryaccjunctiondetails(childaccountid, parentaccounttypeid).

sql ms-access