June 8, 2016 at 11:57 am
1. If you need all the rows in a table, which provides a lower execution cost?
Selecting * from a particular table that is well indexed (SELECT * FROM tbEmployees)
OR
Specifically selecting each column (SELECT fname, lname, deptId FROM tbEmployees)
:smooooth:- f
June 8, 2016 at 12:04 pm
Firemander (6/8/2016)
1. If you need all the rows in a table, which provides a lower execution cost?Selecting * from a particular table that is well indexed (SELECT * FROM tbEmployees)
OR
Specifically selecting each column (SELECT fname, lname, deptId FROM tbEmployees)
:smooooth:- f
Row or columns?
For quick check queries, I will use the *, but in production code I will explicitly name the columns. Naming the columns ensures that the data will be in same format regardless of changes to the underlying table where the dropping and adding of columns could result in difference between SELECT * and SELECT <columnlist>.
Performance wise, there shouldn't be a noticeable difference between them.
June 8, 2016 at 12:07 pm
:w00t: Columns; 'you need all the columns' - sorry about that.
June 8, 2016 at 12:07 pm
Response removed as a result of the change from 'rows' to 'columns'!
If you haven't even tried to resolve your issue, please don't expect the hard-working volunteers here to waste their time providing links to answers which you could easily have found yourself.
June 8, 2016 at 12:29 pm
:w00t: I thought that was a question!... with a typo! I clarified the typo - something you can't always do: You know, like using DELETE rather than SELECT and wiping out your employee records. Its a small typo, but you can't get it back; though you can get your final paycheck.
But this, this was reversible! That's why the author gets to use the 'Post Reply' button. So if he screwed up. He can unscrew. So, please leave the post up... and put away the screwdriver.
:crazy:..and man, that is one UGLY avatar you got there... :crazy:
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