mysql: or/and question

Question

is this:

update batchinfo set instrument='Instrument 17' where
datapath like '%10497%' or 
datapath like '%10506%' or 
datapath like '%10516%' or 
datapath like '%11081%'
and instrument='Instrument 1'

the same as this:

update batchinfo set instrument='Instrument 17' where
datapath like '%10497%' and instrument='Instrument 1' or  
datapath like '%10506%' and instrument='Instrument 1' or  
datapath like '%10516%' and instrument='Instrument 1' or 
datapath like '%11081%' and instrument='Instrument 1'

Answer 1

No - the AND only qualifies datapath like '%11081%'.

Don't take chances - use parentheses. They're cheaper.

Answer 2

No, but these two are equivalent:

update batchinfo 
set instrument='Instrument 17' 
where 
    (datapath like '%10497%' or  
    datapath like '%10506%' or  
    datapath like '%10516%' or  
    datapath like '%11081%') 
    and instrument='Instrument 1' 

and

update batchinfo 
set instrument='Instrument 17' 
where 
    (datapath like '%10497%' and instrument='Instrument 1') or   
    (datapath like '%10506%' and instrument='Instrument 1') or   
    (datapath like '%10516%' and instrument='Instrument 1') or  
    (datapath like '%11081%' and instrument='Instrument 1') 

Answer 3

No. See the mysql operator precedence chart. In general, if you are mixing AND and OR throwing in parenthesis is a good idea.