Most of the DAO header files in src/library/dao have definitions for the names
of tables, and the names of columns in the tables, but they're used
sporadically; quite often, references to them are hardcoded.
I'm writing a new feature (the aforementioned auto-DJ-crates), and the
necessary info is stored in a temporary table, so I'm writing several SQL
queries. I'm just wondering if I should hardcode the table/column references
(which won't automatically get updated if the underlying names change), or try
to write them using the table/column names defined in header files (which makes
the query harder to read).
Here's an example. The comment is the hardcoded, human-readable version, and
following it is the hard-to-read one that'll adapt automatically to changes.
// INSERT INTO temp_autodj_crates (track_id, craterefs, timesplayed,
autodjrefs) SELECT crate_tracks.track_id, COUNT (*), library.timesplayed, 0
FROM crate_tracks, library WHERE crate_tracks.crate_id IN (SELECT id FROM
crates WHERE autodj = 1) AND crate_tracks.track_id = library.id AND
library.mixxx_deleted = 0 GROUP BY crate_tracks.track_id, library.timesplayed;
strQuery = QString ("INSERT INTO " AUTODJCRATES_TABLE
" (" AUTODJCRATESTABLE_TRACKID ", " AUTODJCRATESTABLE_CRATEREFS ", "
AUTODJCRATESTABLE_TIMESPLAYED ", " AUTODJCRATESTABLE_AUTODJREFS ")"
" SELECT " CRATE_TRACKS_TABLE ".%1 , COUNT (*), "
LIBRARY_TABLE ".%2, 0 FROM " CRATE_TRACKS_TABLE ", " LIBRARY_TABLE
" WHERE " CRATE_TRACKS_TABLE ".%4 IN "
"(SELECT %5 FROM " CRATE_TABLE " WHERE %6 = 1) AND "
CRATE_TRACKS_TABLE ".%1 = " LIBRARY_TABLE ".%7 AND " LIBRARY_TABLE
".%3 == 0 GROUP BY " CRATE_TRACKS_TABLE ".%1, " LIBRARY_TABLE ".%2")
.arg (CRATETRACKSTABLE_TRACKID) // %1
.arg (LIBRARYTABLE_TIMESPLAYED) // %2
.arg (LIBRARYTABLE_MIXXXDELETED) // %3
.arg (CRATETRACKSTABLE_CRATEID) // %4
.arg (CRATETABLE_ID) // %5
.arg (CRATETABLE_AUTODJ) // %6
.arg (LIBRARYTABLE_ID); // %7
Which should I do?
Pretty soon, I'll make a blueprint for the auto-DJ-crates feature.
Steven Boswell
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