Help! Need to update a table if a matching value is found in another table.

[sptrsn]

During a select statement, I was doing a lookup on the fly, checking to see if there was a matching value in a second table. The tables have become large enough that it's causing huge speed issues.

 

I don't need any data from the second table. I just need to know if a matching value exists.

 

So, I created a "tracking" field in table 1. My plan was to periodically do an update query and simply set a "1" or a "0" in the tracking field in the first table, IF there was a matching value in the second table. Then I could just add some conditional formatting or whatever, to have a visual clue that table 2 has data for me.

 

I can't figure out how to do it. I've been searching for examples for two hours and can't seem to figure it out.

 

Could one of you, who are obviously smarter than me, give me a clue how to go about this?

 

I've tried all kinds of retarded stuff.

It seems to me that it would be something like this... (but obviously these doesn't work)

UPDATE t1 SET `match` = '1' WHERE t1.apn = t2.apn 
or this
update t1 set match ='1' where select * from t1 as t1 join(select * from t2)t2 on t1.apn=t2.apn

[fenway]

update t1 inner join t2 on ( t1.apn=t2.apn ) set t1.match = 1 where (....)

[sptrsn]

That works beautifully! Thank you very much.