function - Out of the two sql queries below , suggest which one is better one. Single query with join or two simple queries? -

assuming result of first query in a) (envelopecontrolnumber,partnerid,docfileid) = (000000400, 31,35)

a)

select envelopecontrolnumber, partnerid, docfileid  envelopeheader  envelopeid ='lt01env1107010000050';  select count(*)  envelopeheader  envelopecontrolnumber = '000000400'    , partnerid= 31 , docfileid<>35 ; 

or

b)

select count(*)   envelopeheader  join envelopeheader b on a.envelopecontrolnumber = b.envelopecontrolnumber                         , a.partnerid= b.partnerid                         , a.envelopeid = 'lt01env1107010000050'                         , b.docfileid <> a.docfileid; 

i using above query in sql function. tried queries in pgadmin(postgres), shows 16ms a) , b). when tried queries b) separately on pgadmin. still shows 16 ms separately each 1 - making 32ms b) - wrong because when run both queries in 1 go b), shows 16 ms. please suggest 1 better. using postgres database.

the time displayed includes time :

• send query server
• parse query
• plan query
• execute query
• send results client
• process results

try simple query "select 1". you'll 16 ms too.

it's quite measuring ping time server.

if want know how time on server query uses, need explain analyze.