Crosstab using PostgreSQL - postgresql

Question

I have table table1 which consist of following details.
Example:
create table table1
(
slno varchar(10),
joiningdate date,
joiningtime time
);
Inserting some rows:
insert into table1 values('a1','09-08-2011','10:00:00');
insert into table1 values('a1','09-08-2011','10:00:00');
insert into table1 values('a2','19-08-2011','11:00:00');
insert into table1 values('a2','20-08-2011','12:00:00');
Now I need to display it into following format:
slno joiningdate 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23
--------------------------------------------------------------------------------------------------------------------------------------
a1 09-08-2011 2
a2 19-08-2011 1
a2 20-08-2011 1
For which I have tried the following script:
select *
from crosstab('
select slno,joiningdate , to_char(joiningtime, ''HH24'') as tc, count(tc)::int
from table1
group by 1,2,3,4
order by 1,2,3,4'
,$$VALUES('01'),('02'),('03'),('04'),('05'),('06'),('07'),('08'),('09'),('10'),
('11'),('12'),('13'),('14'),('15'),('16'),('17'),('18'),('19'),('20'),
('21'),('22'),('23')$$)
as ct(slno varchar,joiningdate date,"01" int,"02" int,"03" int,"04" int,"05" int,"06" int,"07" int,"08" int,"09" int,"10" int,
"11" int,"12" int,"13" int,"14" int,"15" int,"16" int,"17" int,"18" int,"19" int,"20" int,
"21" int,"22" int, "23" int);
But got stuck how to count tc(joiningtime hours) and add it to appropriate column.

Answer 1

First, produce a series of rows with the hourly counts.
select
slno, joiningdate,
hour,
sum(case when extract(hour from joiningtime) = hour then 1 end)
from table1
cross join generate_series(0,23) h(hour)
group by slno, joiningdate, hour;
then, because crosstab can't deal with multiple column row keys, consolodate the row key using a composite type:
CREATE TYPE ctrowid as ( slno text, joiningdate date );
select
ROW(slno, joiningdate) :: ctrowid,
hour,
sum(case when extract(hour from joiningtime) = hour then 1 end)
from table1
cross join generate_series(0,23) h(hour)
group by slno, joiningdate, hour
order by 1,2;
so the query produces tuples of (rowid, category, value) as required by crosstab. Then wrap it in a crosstab, e.g.
SELECT
*
FROM
crosstab('
select
ROW(slno, joiningdate)::ctrowid,
hour::text,
sum(case when extract(hour from joiningtime) = hour then 1 end)::integer
from table1
cross join generate_series(0,23) h(hour)
group by slno, joiningdate, hour
order by 1, 2
')
ct(rowid ctrowid, h0 integer, h1 integer, h2 integer, h3 integer, h4 integer, h5 integer, h6 integer, h7 integer, h8 integer, h9 integer, h10 integer, h11 integer, h12 integer, h13 integer, h14 integer, h15 integer, h16 integer, h17 integer, h18 integer, h19 integer, h20 integer, h21 integer, h22 integer, h23 integer);
producing:
rowid | h0 | h1 | h2 | h3 | h4 | h5 | h6 | h7 | h8 | h9 | h10 | h11 | h12 | h13 | h14 | h15 | h16 | h17 | h18 | h19 | h20 | h21 | h22 | h23
-----------------+----+----+----+----+----+----+----+----+----+----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----
(a1,2011-08-09) | | | | | | | | | | | 2 | | | | | | | | | | | | |
(a2,2011-08-19) | | | | | | | | | | | | 1 | | | | | | | | | | | |
(a2,2011-08-20) | | | | | | | | | | | | | 1 | | | | | | | | | | |
(3 rows)
You can then unpack the rowid into separate fields in an outer query if you want.
Yes, the need to specify all the columns is ugly, and makes crosstab much less useful than it should be.

Answer 2

I'm sure there is a more efficient way of doing this, but this query should give you what you are looking for. I only provided a portion of your table, but I'm sure you can write out the rest.
SELECT DISTINCT ON(slno,joiningdate) slno,joiningdate,
CASE WHEN joiningtime = '01:00:00' THEN count(*) OVER (PARTITION BY joiningtime) ELSE NULL END AS "01",
CASE WHEN joiningtime = '02:00:00' THEN count(*) OVER (PARTITION BY joiningtime) ELSE NULL END AS "02",
CASE WHEN joiningtime = '03:00:00' THEN count(*) OVER (PARTITION BY joiningtime) ELSE NULL END AS "03",
CASE WHEN joiningtime = '10:00:00' THEN count(*) OVER (PARTITION BY joiningtime) ELSE NULL END AS "10",
CASE WHEN joiningtime = '11:00:00' THEN count(*) OVER (PARTITION BY joiningtime) ELSE NULL END AS "11",
CASE WHEN joiningtime = '12:00:00' THEN count(*) OVER (PARTITION BY joiningtime) ELSE NULL END AS "12"
FROM table1