Snowflake - How to pass a NULL parameter in a stored procedure? - snowflake-cloud-data-platform

Question

CREATE PROCEDURE GET_DATE(START_DATE VARCHAR, IS_SET VARCHAR(1), TIME_ZONE VARCHAR)
...
if (START_DATE) {
}
CALL GET_DATE(NULL, '1', 'PST');
What is the proper way to pass the default NULL value to stored procedure?
(NULL, '1', 'PST') doesn't execute and it just returns a row that says "NULL".

Answer 1

When you create the procedure there are two optional parameters CALLED ON NULL INPUT and RETURNS NULL ON NULL INPUT | STRICT:
CALLED ON NULL INPUT means the procedure is executed when you pass a NULL value and the procedure has to handle the NULL values.
RETURNS NULL ON NULL INPUT | STRICT means the procedure won't execute when you pass a NULL value. Instead the procedure just returns NULL.
The first parameter is default - maybe you set it accidentally by copying the CREATE PROCEDURE-code from somewhere else. More info: https://docs.snowflake.com/en/sql-reference/sql/create-procedure.html
Another hint is about case-sensitivity: Maybe inside your procedure your parameter is referred to by its lowercase name, but Snowflake has automatically converted the name to uppercase. See here: https://docs.snowflake.com/en/sql-reference/stored-procedures-usage.html#stored-procedure-or-udf-unexpectedly-returns-null
And one last thing you may think about is the code of your procedure. Maybe passing NULL works fine but your code produces a NULL value and thus the returned NULL value is correct.

Answer 2

Please refer to https://community.snowflake.com/s/article/Store-Procedure-and-Nulls
In Javascript store-procedures nulls are handled in a special way, SQL Nulls automatically get converted into 'UNDEFINED' inside the store procedure. The end-user should always take care of this by replacing its value inside the procedure, please have a look at the documentation page for further details.
The following are the three important scenarios/use-cases reflecting this behavior.
Call of the procedure with null values: when we pass nulls, as soon
as it comes inside the procedure they get transformed by 'undefined'.
Shows "undefined" within the procedure: Inside the procedure, if the
same passed parameter with Null is used then it will show
'undefined'. if the same value is inserted into a table, the table
will contain 'undefined' instead of null. Use replace inside the
procedure to cope with this.
Should return null values as result: If procedure returns
'undefined' it will be automatically converted as NULL outside the
procedure.
so to handle null, use piece of code mentioned below
if(START_DATE === undefined){
do something to handle NULL
}