Single and Group Functions

I studied up on Oracle functions. Then I took a review test. I only got a 7 out of 10. In my book that is a grade of C. Nobody wants a C average student doing their crucial Oracle development. So I need a lot more practice. Here are some times that I have learned during my testing.

The TO_CHAR and TO_DATE functions take a value to format and a format string. I have a mental block where I cannot remember whether the value or the format string comes first. Here is a simple way to remember it. The format string always comes second in the list of arguments.

Previously I have written about the finer points of SQL. Here is an additional point to note. You cannot use an alias in a GROUP BY clause. Speaking of the GROUP BY clause, it is required if you have a group function in the SELECT clause and also have something other than a constant in the SELECT clause.

Finally I will share a little more trivia about Oracle functions. All of the trigonometry functions operate on units of radians (not degrees). And note that the COUNT function includes NULL values in its count. That's all for now. Maybe next time I will discuss joins and subqueries.