SQL query involving data from multiple tables

Question

I am really new to SQL & it would be really helpful if somebody can help with one simple query that I am struggling to write.

list ( plid, fid )

files ( fid, filename )

I want to get the fid & filename from the above tables where plid=3. The steps would be 1) Get the fid values from table "list" where plid=x 2) Get the filename from "files" for all the matched fid in table "list".

Answer 1

这正是您需要JOIN语句的地方：

SELECT list.fid, files.filename FROM list INNER JOIN files ON files.fid = list.fid WHERE files.plid = 3