The MERGE and Other Info

Day 1 of my Oracle PL/SQL programming course covered so much that I am still blogging about it. The instructor showed us an example relating to the Oracle MERGE functionality. I have heard of MERGE. But I did not know what it did. Our instructor then gave us the executive summary of what MERGE was.

You might have a Production database table with new information that you wish to promote to your data warehouse. You can accomplish this with a MERGE statement. It determines whether the data warehouse target already has a row for the Production one. If so, it is MATCHED and you do an UPDATE. Otherwise you perform an INSERT into your data warehouse.

Our instructor went over some other facts that were not in the class presentation materials. He explained that variables using %TYPE for definition, as well as the rest of the declaration section, are evaluated at compile time.

We also debunked the term predicates. These are parts of your WHERE clause. I guess that is just a fancy way of saying it. I have heard the data mining people talk about the complexity of their predicates. That just means that have a lot in their WHERE clauses.