sql server - SQL: Struggling to join 3 tables from a many-to-many relationship -
i have 3 tables:
users - username procedures - seriesnum,procnum (composite pkey),description,currentrev usersprocedures - username,seriesnum,procnum,revtrained,leveltrained,datetrained
how query shows, each user, procedures, , if trained in procedures, values in usersprocedures table (and if they're not trained, values come null because they're not present).
the closest i've got query:
select procedures.seriesnum,procedures.procnum,description,currentrev,revtrained,leveltrained,datetrained,users.username procedures,users left join usersprocedures on usersprocedures.username = users.username
however doesn't work because values it's pulling usersprocedures table same each procedure, rather being unique each procedure.
-- select whatever columns select p.*, u*, pu.* -- cross join conmbines rows both tables procedures p cross join users u -- add exp mix left join usersprocedures pu on pu.username = u.username , p.seriesnum = pu.seriesnum , p.procnum = pu.procnum
Comments
Post a Comment