Simply join 2 tables without condition and cross join, MySQL

table 1:

value
a
b

table 2:

value
c
d
e

I need to get this result:

value	value
a	c
b	d
NULL	e

So, it's like Simple join, when row from 1st table matches corresponding(by order) row in 2nd table without any condition.

As a kind of workaround, I thought out this one:

SELECT value, "table1" AS src FROM t1
UNION ALL
SELECT value, "table2" AS src FROM t2

which gives:

value	src
a	table1
b	table1
c	table2
d	table2
e	table2

In general it's appropriate, but can it be done as I showed in necessary result above?

Solution

You did not mention any column which will define the order, in that case value column is used to add a ordering using ROW_NUMBER().

CTE table1_with_rownum and table2_with_rownum will assign the order.
These datasets are then joined based on rownum so that order is maintained and the result sets are unioned to remove any duplicates.

Fiddle

WITH table1_with_rownum AS (
    SELECT value, ROW_NUMBER() OVER (ORDER BY value) AS rownum
    FROM table1
),
table2_with_rownum AS (
    SELECT value, ROW_NUMBER() OVER (ORDER BY value) AS rownum
    FROM table2
)

SELECT 
    t1.value AS value1, 
    t2.value AS value2
FROM table1_with_rownum t1
LEFT JOIN table2_with_rownum t2 ON t1.rownum = t2.rownum 

UNION

SELECT 
    t1.value AS value1, 
    t2.value AS value2
FROM table1_with_rownum t1
RIGHT JOIN table2_with_rownum t2 ON t1.rownum = t2.rownum
ORDER BY value1;

Output