Joining tables without JOIN or subqueries

I have two tables names T1 and T2 like below,

T1
---
slNo  value
----  ------
1      A
2      NULL
3      C

T2
---
slNo  value
----  ------
1      NULL
2      B
3      NULL
Based on these two tables, I need a third table like the following one:
T3
--
slNo  value
----  ------
1      A
2      B
3      C
So, I need a SQL query without using any JOIN operations, nested queries or subqueries to get the third table T3.


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Without using joins or subqueries, you're really limiting my choice of tools. But it can be done. Here goes:

select slNo, value from T1 where value is not null
union 
select slNo, value from T2 where value is not null;

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This was first published in March 2002

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