EXPERT RESPONSE
We've been getting a number of this type of question lately: short,
and simple on the surface. Short questions are wonderful, because they
leave more room for the answer. Simple questions are even better,
as long as they aren't too simple.
In this case, there are two ways to do it.
select distinct
col1
, col2
from daTable
This method uses the standard SQL keyword DISTINCT. All distinct
combinations of values in two columns are shown. (It could be two, or
10, or even just one column.) The "distinctness" applies to the
entire row produced by the query. Every result row
is completely distinct.
select col1
, col2
from daTable
group
by col1
, col2
This method uses the standard SQL keywords GROUP BY. All distinct
combinations of values in two columns are shown. (It could be two, or
10, or even just one column.) The "distinctness" applies to the
columns in the GROUP BY. Every result row will
be completely distinct in those two columns.
If you wanted distinct rows by those two columns, but with additional
columns as well, then the question was indeed not as simple as it first
appeared. In that case, perhaps the answer
DISTINCT is not a function (26 September 2005) may help.
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