snowflake handle null while reading csv file - snowflake-cloud-data-platform

Question

I am trying to load a CSV file from S3. which has a null value in the integer type data field in the snowflake table.
So I try to use IFFNULL function but gets the error.
Numeric value 'null' is not recognized.
For example when I try
select IFNULL(null,0)
I get the answer as 0.
but the same thing when I try while reading the CSV file won't work
select $1,$2,ifnull($2,0)
from
#stage/path
(file_format => csv)
I get the null not recognized Error.
and it fails when $2 is null.
My csv format is as below.
create FILE FORMAT CSV
COMPRESSION = 'AUTO' FIELD_DELIMITER = ','
RECORD_DELIMITER = '\n' SKIP_HEADER = 0
FIELD_OPTIONALLY_ENCLOSED_BY = '\042'
TRIM_SPACE = FALSE
ERROR_ON_COLUMN_COUNT_MISMATCH = TRUE ESCAPE = '\134'
ESCAPE_UNENCLOSED_FIELD = '\134' DATE_FORMAT = 'AUTO'
TIMESTAMP_FORMAT = 'AUTO' NULL_IF = ('\\N');
Basically, I am just trying to convert null to 0, when reading from the stage.

Answer 1

The null string literal could be handled by setting NULL_IF:
CREATE FILE FORMAT CSV
...
NULL_IF = ('null', '\\N');

Answer 2

I used the second option listed in the Snowflake documentation specifying FIELD_OPTIONALLY_ENCLOSED_BY=NONE and EMPTY_FIELD_AS_NULL = FALSE in which case I'd need to provide a value to be used for NULLs (NULL_IF=('NULL')
https://docs.snowflake.com/en/user-guide/data-unload-considerations.html
"Leave string fields unenclosed by setting the FIELD_OPTIONALLY_ENCLOSED_BY option to NONE (default), and set the EMPTY_FIELD_AS_NULL value to FALSE to unload empty strings as empty fields.
If you choose this option, make sure to specify a replacement string for NULL data using the NULL_IF option, to distinguish NULL values from empty strings in the output file. If you later choose to load data from the output files, you will specify the same NULL_IF value to identify the NULL values in the data files."
So my query looked something like the following:
COPY INTO #~/unload/table FROM (
SELECT * FROM table
)
FILE_FORMAT = (TYPE = 'CSV' COMPRESSION = 'GZIP'
FIELD_DELIMITER = '\u0001'
EMPTY_FIELD_AS_NULL = FALSE
FIELD_OPTIONALLY_ENCLOSED_BY = NONE
NULL_IF=('NULL'))
OVERWRITE = TRUE;