mysql - Priority executing WHERE clause in JOIN keyword -


i want know, when use where clause following directives join, happen ?

in fact, want know priority of execute. instance, consider below code:

select * tablename1 t1 inner join tablename2 t2 on t1.id=t2.id id='10'

then happen in above code first?

sql select rows id 10 , runs join keyword ? or join keyword runs in first , where clause?

to answer question join runs first, if want filter try query

select *  (   select *   tablename1   id='10') t1,   (   select *   tablename2    id = '10' ) t2

update: others suggest checking execution plan understand how query performs, still if want decide on own, better yourself.

update 2: @giorginakeuri points. mentioned in comments after change inner queries inner join not needed. simple cartesian join enough.

read art of sql more info on sql optimisations.

for more advanced knowledge try sql tuning


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