Forum Discussion
Left outer Join - but only selected columns from both tables
Hi - I feel this should be easy but I can't work it out. I have table A - it has let's say 50 columns, it's quite big. I have table B - let's say it also has 50 columns. I need to merge thes...
Are you sure that creating a reference to your table and doing the join with the reference will hit the table twice? Normally query folding would just hit a table once, but there are conditions and the differ per connector and DBMS. Best way to see what happens is to give it a try...
By the way: Making a reference is NOT copying. It does make any differene in performance if you have a query with 10 steps or 2 queries with 5 steps each (provided the steps remain the same off course...)