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Well, lets say your rows are: id|score|last_name 1|11|smith 2|22|jones 3|33|smith 4|44|jones Query we are pretending is valid is: SELECT id, last_name FROM
by justin_vanw 15y ago
Well, lets say your rows are:
id|score|last_name
1|11|smith
2|22|jones
3|33|smith
4|44|jones
Query we are pretending is valid is:
SELECT id, last_name FROM table GROUP BY last_name;
What rows are returned? I expect to see something like:
?|?|smith
?|?|jones
However, what ? is isn't clear. Could we get a row like 1|33|smith ?
In SQL, all selected columns must be part of the group by or inside an aggregate.