问题
using PHP and MySQL
i have grabbed an array of facebook user ids from facebook.
Now i want to find the corresponding username in my application for this array.
Clearly in my application the user table contains unique username and unique fb_uid values.
my rudimentary understanding oof programming led me to 2 ways:
1) use a loop and run through the array of fb_uid and find the username one by one.
OR
2) create a monster query like select distinct(username) from users where fb_uid = value1 OR fb_uid = value2 ...
so is there a better way out?
Thank you.
回答1:
Use SQL's IN operator instead:
select distinct(username) from users where fb_uid in (value1, value2, ...)
http://www.w3schools.com/SQl/sql_in.asp
回答2:
If your list of fb_uids is big (say, more than 100 or 500 r 1000 hundred ids), I wouldn't go with the "or" way : too many "or" like this will hurt the DB, I think.
But doing one query per id is not really good either...
So what about a mix of those two ideas ? Doing one query per, say, 50 or 100 fb_uids ?
And, instead of using lots or OR, you can go with IN ; a bit like this :
select distinct(username) from users where fb_uid IN (id1, id2, id3, ...)
Not sure it'll change anything for the DB, but, at least, it's looking better ^^
Only thing is you shouldn't use too many ids in the IN ; so, doing a couple of queries, with between 50 and 500 ids each time might be the way to go.
And to help you a bit further, you might need to take a look at array_slice, to extracts "slices" of your fb_uids array...
回答3:
There's another MySQL function: MATCH AGAINST
SELECT * FROM customer WHERE status = 1 AND MATCH (person, city, company, zipcode, tags) AGAINST ('".$searchstring."' IN BOOLEAN MODE)
Your inputstring will be searched in different columns.
Maybe you can reconsider your sql statement if you didn't knew this function.
来源：https://stackoverflow.com/questions/1273259/how-to-optimize-mysql-query-if-i-have-too-many-or-operators-in-my-query