Question: Part of a complex query that our app is running contains the lines:
...(inner query)

```
SELECT
...
NULL as column_A,
NULL as column_B,
...
FROM
...

```

This syntax of creating columns with **null** values is not allowed in DB2 altough it is totally OK in **MSSQL** and **Oracle** DBs.
Technically I can change it to: 

```
'' as column_A,
'' as column_B, 

```

But this doesn't have exactly the same meaning and can damage our calculation results.
How can I create columns with null values in DB2 using other syntax??

Answer: 
DB2 is strongly typed, so you need to tell DB2 what kind of column your NULL is:

```
select 
   ...
   cast(NULL as int) as column_A,
   cast(NULL as varchar(128)) as column_B,
   ...
FROM
   ...

```
For Db2 LUW, since version 9.7, you can (if you like) use the `NULL` value without explicitly casting it to a particular data type.

`NULL` on it's own will be implicitly cast to `VARCHAR(1)`. This knowledge center page will show what happens in other cases: [Determining data types of untyped expressions](https://www.ibm.com/support/knowledgecenter/en/SSEPGG_11.1.0/com.ibm.db2.luw.sql.ref.doc/doc/r0053561.html "https://www.ibm.com/support/knowledgecenter/en/SSEPGG_11.1.0/com.ibm.db2.luw.sql.ref.doc/doc/r0053561.html")

Examples

```
db2 "describe values ( NULL, + NULL, NULL || NULL  )"

 Column Information

 Number of columns: 3

 SQL type              Type length  Column name                     Name length
 --------------------  -----------  ------------------------------  -----------
 449   VARCHAR                   1  1                                         1
 997   DECFLOAT                 16  2                                         1
 449   VARCHAR                 508  3                                         1

```

and

```
db2 "describe values NULL, 1"

 Column Information

 Number of columns: 1

 SQL type              Type length  Column name                     Name length
 --------------------  -----------  ------------------------------  -----------
 497   INTEGER                   4  1                                         1

```