I need to create a table with column from two other tables.
I also need to have condition on several of the column (typically testing if the value of the row is not null).
I have tried several ways, but I only managed to add as much column as I want from one other table, without any conditions testing. 

here basically what I'd like to make :

```
CREATE TABLE target_table
AS(        
SELECT column1 FROM source_table1 WHERE column1 IS NOT NULL
UNION
SELECT column2, column3 FROM source_table1
UNION
SELECT column1 FROM source_table2
)

```

with this query I get the : "query block has incorrect number of result columns" error.

I have tried also this :

```
CREATE TABLE target_table
AS(        
SELECT column1 FROM source_table1 WHERE column1 IS NOT NULL
UNION
SELECT column2 FROM source_table1
)

```

It "works" as there are no errors, but none of the column2 rows are in my target\_table.
This is probably trivial but I have been unable to find any answer of these kind of table creation with condition and several column origin..