Re: SQL Question - Select * versus selecting all fields individually

Hi Glenn,

Option c is good for performance and to avoid level-check problems -- if new fields are added, or fields you aren't using are changed, your program will still run correctly.

I've used option a with the externally-defined DS when I know the file isn't going to change a lot but the program might (i.e. might use more fields), and performance is acceptable -- usually interactive inquiry-type programs.

I haven't tested it, but I think there are a lot of other factors that affect performance more directly than * vs a list of fields, e.g. having the correct indices.

*Peter Dow* /
Dow Software Services, Inc.
909 793-9050
pdow@xxxxxxxxxxxxxxx <mailto:pdow@xxxxxxxxxxxxxxx> /

Glenn Gundermann wrote:

Hi Everyone,

Someone here with lots of SQL experience but none with System i says:
"My 2 cents on your code is not to use Select *. Always list the columns
solely for performance reasons."

My thinking is to select all columns into an externally described DS based
on the table so I have everything I might need.

I could:
(a) keep my code as is, using select *, or
(b) select every field individually
(c) only select the fields I need, or

What is everyone doing when using embedded SQL?

Tks,

Glenn Gundermann
ggundermann@xxxxxx
(647) 272-3295