Convert rows to cols by crosstab()

row2col_crosstab_example.sql

CREATE EXTENSION IF NOT EXISTS tablefunc;

CREATE TEMP TABLE my_rows (age integer, gender varchar, val integer);
INSERT INTO my_rows VALUES (10, 'M', 11), (10, 'W', 12), (10, 'A', 13);
INSERT INTO my_rows VALUES (20, 'M', 21), (20, 'W', 22);
INSERT INTO my_rows VALUES                               (30, 'A', 33);

-- rows
SELECT * FROM my_rows;
--  age | gender | my_value
-- -----+--------+----------
--   10 | M      |       11
--   10 | W      |       12
--   10 | A      |       13
--   20 | M      |       21
--   20 | W      |       22
--   30 | A      |       33
-- (6 rows)

-- cols
SELECT * FROM crosstab('SELECT * FROM my_rows ORDER BY 1,2', $$VALUES ('M'::varchar), ('W'::varchar), ('A'::varchar)$$)
                       AS ct(age integer, M_val integer, W_val integer, A_val integer);
--  age | m_value | w_value | a_value
-- -----+---------+---------+---------
--   10 |      11 |      12 |      13
--   20 |      21 |      22 |
--   30 |         |         |      33
-- (3 rows)

-- http://stackoverflow.com/questions/3002499/postgresql-crosstab-query