Create a pivot table with PostgreSQL

Question

Suppose I have a table in Postgres called listings that looks like this:

id    neighborhood    bedrooms    price
1     downtown        0           256888
2     downtown        1           334000
3     riverview       1           505000
etc.

How do I write a crosstab query that shows the average price per bedrooms as the columns and neighborhoods as the rows?

The output of the query should look something like this (numbers are made up, columns are the bedrooms):

            0       1       2       3
riverton    250000  300000  350000  -
downtown    189000  325000  -       450000

Answer 1

First compute the average with the aggregate function avg():

SELECT neighborhood, bedrooms, avg(price)
FROM   listings
GROUP  BY 1,2
ORDER  BY 1,2;

Then feed the result to the crosstab() function as instructed in great detail in this related answer:

• PostgreSQL Crosstab Query

Answer 2

The best way to build pivot tables in Postgres are CASE expressions.

SELECT neighborhood,
       round(avg((CASE WHEN bedrooms = 0 THEN price END)), 2) AS "0",
       round(avg((CASE WHEN bedrooms = 1 THEN price END)), 2) AS "1",
       round(avg((CASE WHEN bedrooms = 2 THEN price END)), 2) AS "2",
       round(avg((CASE WHEN bedrooms = 3 THEN price END)), 2) AS "3"
FROM listings
GROUP BY neighborhood;

Running this on the question data yields

NEIGHBORHOOD                  0          1          2          3
-------------------- ---------- ---------- ---------- ----------
downtown                 256888     334000       NULL       NULL
riverview                  NULL     505000       NULL       NULL

Answer 3

Another solution that implement with filter:

SELECT neighborhood,
   avg(price) FILTER (WHERE bedrooms = 0) AS "0",
   avg(price) FILTER (WHERE bedrooms = 1) AS "1",
   avg(price) FILTER (WHERE bedrooms = 2) AS "2",
   avg(price) FILTER (WHERE bedrooms = 3) AS "3"
FROM listings
GROUP BY neighborhood;