comparing column values when there are nothing in common between tables

Question

I have a need to display the value stored in columns of separate tables where the tables and columns have nothing in common. I just want to compare the content of the rows of each column side-by-side. And just the 1st 10 rows would be sufficient for my purposes. There are no primary keys or common link between the tables.

I have many tables with hundreds of columns to compare. Is there a simple way to do this?

i.e. Table1, column3 | Table2, column6 | Table3, column1

Resulting in something like the following

tbl1col3 | tbl2col6 | tbl3col1
123.9    | abc      | x12
234.0    | bcd      | o23

Using postgresql 9.6, pgadmin4 v3.5

Answer 1

like this perhaps.

WITH t1 AS ( SELECT col3 AS tbl1col3,row_number()OVER() FROM tbl1 limit 10)
    ,t2 as ( select col6 AS tbl2col6,row_number()OVER() FROM tbl2 limit 10)
    ,t3 as ( select col1 AS tbl3col1,row_number()OVER() FROM tbl3 limit 10)
SELECT tbl1col3, tbl2col6, tbl3col1 
FROM t1 
    FULL OUTER JOIN t2 USING (row_number)
    FULL OUTER JOIN t3 USING (row_number)
;