SQL: Dynamically Transposing Column as Row in Chartio - sql

Question

I would love to have your help transposing this table's column into a row. I am trying to have the Project Names (column 1) each becoming their own column header with the MUVs value entered as the column value.
I have read through 20+ threads on this topic, but they are using different SQL packages and code that I am unable to use.
The ideal solution would modify this query to create the desired query output:
Current Query:
SELECT
cust_gae_account.project_name as "Project Name",
cust_be_project_usage.unique_visitor_count as "MUVs",
cust_be_project_usage.billing_period_start as "Month"
FROM
cust_be_project_usage
INNER JOIN
cust_gae_account
ON cust_gae_account.account_id = cust_be_project_usage.project_id
WHERE
cust_be_project_usage.admin_account_id = {ACCOUNT_ID}
Current Query Output:
Project Name | MUVs | Month
-----------------------------------------------------
ProjectAAAAAZ | 68000 | Jun 01, 2016
DynamicName | 3200 | Jun 01, 2016
ProjectAAAAAZ | 21000 | May 01, 2016
DynamicName | 4500 | May 01, 2016
CustomProject | 117000 | Jun 01, 2016
CustomProject | 118400 | May 01, 2016
Desired Query Output:
Project Name | CustomProject | ProjectAAAAAZ | DynamicName
-------------------------------------------------------------------
Jun 01, 2016 | 117000 | 68000 | 3200
May 01, 2016 | 118400 | 21000 | 4500
Notes:
We are using PostgreSQL via Chartio, we can only use base SQL
We cannot use custom functions sadly
Names and number of projects is dynamic, varies from 1 to 20
MUVs are always numeric, there are no duplicates

Answer 1

You can use crosstab https://www.postgresql.org/docs/9.1/static/tablefunc.html , but it will only work with a static list of columns. So you need a dynamic query. You need to define that query, and execute it.
EXECUTE ('SELECT * FROM crosstab(
\'SELECT
cust_be_project_usage.billing_period_start as "Month",
cust_gae_account.project_name as "Project Name",
cust_be_project_usage.unique_visitor_count as "MUVs"
FROM
cust_be_project_usage
INNER JOIN
cust_gae_account
ON cust_gae_account.account_id = cust_be_project_usage.project_id
WHERE
cust_be_project_usage.admin_account_id = {ACCOUNT_ID}\',
\'SELECT
cust_gae_account.project_name as "Project Name"
FROM
cust_be_project_usage
INNER JOIN
cust_gae_account
ON cust_gae_account.account_id = cust_be_project_usage.project_id
WHERE
cust_be_project_usage.admin_account_id = {ACCOUNT_ID}\')
AS ( "Project Name" date, ' ||
(SELECT
string_agg(cust_gae_account.project_name, ' int,')
FROM
cust_be_project_usage
INNER JOIN
cust_gae_account
ON cust_gae_account.account_id = cust_be_project_usage.project_id
WHERE
cust_be_project_usage.admin_account_id = {ACCOUNT_ID}) || ' int'
|| ' )')
I am not able to test it though. It SHOULD work, but my suspicions are that it might not, in these situations:
Concatenating to a scalar formed by a query (might need to use a variable for that one)
I might have mixed up a column somewhere
Not sure how you pass the {ACCOUNT_ID} parameter so you might need to change that too