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| author | Bruce Momjian <bruce@momjian.us> | 2022-08-31 22:19:06 -0400 |
|---|---|---|
| committer | Bruce Momjian <bruce@momjian.us> | 2022-08-31 22:19:06 -0400 |
| commit | fede15417225c08479fc6cd10812a25826c65f86 (patch) | |
| tree | 2872b745fcecfedd67f70081732b0f19d007e9c0 | |
| parent | fbd597e0b80d5590594be187a7c51e29ac7c5ca2 (diff) | |
| download | postgresql-fede15417225c08479fc6cd10812a25826c65f86.tar.gz postgresql-fede15417225c08479fc6cd10812a25826c65f86.zip | |
doc: use FILTER in aggregate example
Reported-by: michal.palenik@freemap.sk
Discussion: https://postgr.es/m/163499710897.684.7420075366995883688@wrigleys.postgresql.org
Backpatch-through: 10
| -rw-r--r-- | doc/src/sgml/query.sgml | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/doc/src/sgml/query.sgml b/doc/src/sgml/query.sgml index 6f31a5a1d62..8243bf51af8 100644 --- a/doc/src/sgml/query.sgml +++ b/doc/src/sgml/query.sgml @@ -726,19 +726,20 @@ SELECT city, max(temp_lo) which gives us one output row per city. Each aggregate result is computed over the table rows matching that city. We can filter these grouped - rows using <literal>HAVING</literal>: + rows using <literal>HAVING</literal> and the output count using + <literal>FILTER</literal>: <programlisting> -SELECT city, max(temp_lo) +SELECT city, max(temp_lo), count(*) FILTER (WHERE temp_lo < 30) FROM weather GROUP BY city HAVING max(temp_lo) < 40; </programlisting> <screen> - city | max ----------+----- - Hayward | 37 + city | max | count +---------+-----+------- + Hayward | 37 | 5 (1 row) </screen> @@ -748,7 +749,7 @@ SELECT city, max(temp_lo) names begin with <quote><literal>S</literal></quote>, we might do: <programlisting> -SELECT city, max(temp_lo) +SELECT city, max(temp_lo), count(*) FILTER (WHERE temp_lo < 30) FROM weather WHERE city LIKE 'S%' -- <co id="co.tutorial-agg-like"/> GROUP BY city |