Add multiple future dates at one time into redshift SQL - sql

Question

Now I have a table that with the detail as follows:
Date Campaign Visits Orders Revenue
.... .... .... .... ....
Jun-18 Promotion01 10 1 120
Let's say it called table A
Now because of report purpose, I would like to add in new dates like as follows
Date Campaign Visits Orders Revenue
Jul-18 NULL 0 0 0
Aug-18 NULL 0 0 0
Sep-18 NULL 0 0 0
.... .... .... .... ....
Dec-18 NULL 0 0 0
I would like to use the union to add in only the date data.
I tried the dateadd function in Amazon redshift with the following command
SELECT
to_char(dateadd(month, 18, '01-01-2017'),'yyyy-MM') as plus30,
NULL,
0,
0,
0
It returns the date, however it just return only 1 row i.e
Date Campaign Visits Orders Revenue
Jul-18 NULL 0 0 0
If I want to return multiple row like how it is shown before, except of joining 1 by 1, what should I do then?
Many thanks for your help!

Answer 1

Frankly, the easiest way to do these sorts of tasks is to make an Excel spreadsheet, fill-in all the desired values, save it as CSV and then use COPY to load it into Redshift. This gives you the benefit of a nice interface to create the data without having to play around with SQL.
The reason you are only getting one line is that SELECT normally works off a table of data, returning one result per row of input data. You have not specified a table, so it is returning only one row.
Fortunately, you can use generate_series() in some situation to simulate data:
SELECT
to_char(date '01-01-2017' + counter * interval '1 month','yyyy-MM') as plus30,
NULL,
0,
0,
0
FROM generate_series(1, 12) as counter
This generates:
2017-02 (null) 0 0 0
2017-03 (null) 0 0 0
2017-04 (null) 0 0 0
2017-05 (null) 0 0 0
2017-06 (null) 0 0 0
2017-07 (null) 0 0 0
2017-08 (null) 0 0 0
2017-09 (null) 0 0 0
2017-10 (null) 0 0 0
2017-11 (null) 0 0 0
2017-12 (null) 0 0 0
2018-01 (null) 0 0 0
(Your question showed yyyy-MM in the SQL, but Mon-YY in the output, so please adjust accordingly. It is normally better to use yyyy-MM because it is easily sortable as both a number and a string.)