You might have noticed the text that appears at
the top of each column in the SELECT output--the column label.
The label usually is the name of the selected column. However, you can control
the text that appears at the top of each column by using the AS keyword.
For example, Figure replaces the default column
label firstname with the column label buddy.
test=> SELECT firstname AS buddy FROM friend ORDER BY buddy;
buddy
-----------------
Cindy
Jack
Mark
Mike
Sam
(5 rows)
You might have noticed that the query in Figure on
page has the column label ?column?. The
database server returns this label when there is no suitable label. In that
case, the result of an addition does not have an appropriate label. Figure
shows the same query with an appropriate label added using AS.
test=> SELECT 1 + 3 AS total;
total
-------
4
(1 row)