Re: Implicitly hidden column & EXTNAME D/S

An interesting thought, Justin - the evidence of the I-specs that the pre-compiler adds suggests you are right.

Now that also suggests to me that, if one uses SELECT *, then, if columns are added, they will not be seen - no I-spec for the new columns.

Or is this just a Monday-morning fancy I'm going through?

Cheers
Vern

On 5/4/2020 10:15 AM, Justin Taylor wrote:

Unless I'm mistaken, the pre-compiler resolves the SELECT * at compile-time, so the result is the same as explicitly listing the columns.


-----Original Message-----
From: David Gibbs via RPG400-L [mailto:rpg400-l@xxxxxxxxxxxxxxxxxx]
Sent: Friday, May 01, 2020 12:34 PM
To: RPG programming on IBM i <rpg400-l@xxxxxxxxxxxxxxxxxx>
Cc: David Gibbs <david@xxxxxxxxxxxx>
Subject: Re: Implicitly hidden column & EXTNAME D/S

On 5/1/20 12:19 PM, Justin Taylor wrote:

" BTW it is never a good ide to use SELECT *!"

Personally, I'd say "almost never". Can you explain why it's better
for the SELECT (in static SQL) to explicitly list every single column
rather than doing SELECT *?

If a table's structure changes, and you're retrieving into host variables, you will be either missing variables, have too many, or have mismatches.

As Brigitta says, better to list every column you want to retrieve so there is little risk of mismatch.

david


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