On 2007-02-27, Ted Zlatanov <[EMAIL PROTECTED]> wrote: > SELECT fileid FROM tagset WHERE tag = 'A' > INTERSECT > SELECT fileid FROM tagset WHERE tag = 'B'
Oh, yes, you can select single columns. I still wonder about the efficiency of INTERSECT, though. > The known file name is just an extra column in the files table, and > searching for it is fast if the column is indexed. But aren't there limits on the lengths of strings? I seem to recall there being. You could, of course, have one column for each tag up to a maximum number of tags, and sort the tags lexicographically (or by ID, if the IDs listed in a table of tags are used instead), but that might be inefficient with the, say, max. 64 tags? -- Tuomo
