Originally posted by: Nitemare
Got an interview doing AIX and SQL support yet my only experience with SQL is searching a database for what SQL error messages really mean.
Inner and outer joins are the only thing that is somewhat tricky about database design and SQL. It is quite easy to learn. I would say take half a day to get the major concepts right.
Inner joins only link up exact matches.
there are 3 outer joins. left, right, and full
left - inner join both tables but include all "left" table that aren't linked to the "right" table
right - same but with "right" (subjective to your design)
full - include all left and right not included in inner join
then there is the cross-product
all records are matched to all records in other table. (N*M) or (N^2) records produced. not efficient.
I suggest you use something like MS Access and test a few things in a book or something. You will pick up the full concepts very quickly.