how to write the sql for php?

i try to explain this in proper way, i have two tables in mysql, like:
table 1:
id1
topic
........

table 2:
id2
id1 (this id is the id in table1)
....

Now I need get "TOPIC" thru "ID2", Can anyone give me the sql?
thanks

 

I believe this would be correct:

mysql_query("SELECT topic FROM table1 WHERE table1.id1=table2.id2");

 

select `topic` from `table1` where `table1`.`id1` = `table2`.`id2`

 

i run the sql in mysqladmin, it's said
#1109 - Unknown table 'table2 in field list

 

Please check the spelling of the table2/table 2.

 

No, the table names are right. i just need make sure the sql is right.

 

Which query, mine or the other guys?s

 

try this:

(SELECT topic FROM table1 WHERE table1.id1=table2.id1)

OR,

this:

select table1.topic from table1 where table1.id1 = table2.id1

 

i dont think its easy to get understand that without to learn the basic and i would suggest u to go www.php.net and its not a big section of Mysql -> PHP try it. would be the best for u , there are more many options u may want know.

 

You are getting the unknown table2 error because you aren't using table2 in the query...

select table1.topic from table1, table2 where table1.id1 = table2.id1

 

Tobert Plank is right, i just changed the sql, it's return the right result., thank you so much.