Multiple merge statements in a snowflake transaction - sql

Question

I'm new to snowflake and just tried creating a stored procedure to read deltas from a stream table A and execute two merge statements into tables B & C, but I keep getting this error message "Multiple SQL statements in a single API call are not supported; use one API call per statement instead."
Here's my stored procedure. The idea is to call it from a task when system$stream_has_data('tableA')
create or replace procedure write_delta()
return varchar
language sql as
$$
begin transaction;
-- 1/2. load table B
merge into tableB as dest
using tableA as src
on src.id = dest.id
when not matched
then insert (id, value) values( src.id, src.value);
-- 2/2. load tableC
merge into tableC as dest
using tableA as src
on src.id = dest.id
when not matched
then insert (id, value) values( src.id, src.value);
commit;
$$;

Answer 1

Snowflake SQL stored procedures take two forms.
Form 1: A single SQL statement. This is mostly useful when calling from a task to execute a single statment.
Form 2: A Snowflake Scripting block. The following script shows your code converted to a stored procedure with a scripting block:
create or replace table table1 (id int, value string);
create or replace table tableB like table1;
create or replace table tableC like table1;
create or replace stream tableA on table table1;
insert into table1(id, value) values (1, 'A'), (2, 'B');
create or replace procedure myprocedure()
returns varchar
language sql
as
$$
begin
begin transaction;
-- 1/2. load table B
merge into tableB as dest
using tableA as src
on src.id = dest.id
when not matched
then insert (id, value) values( src.id, src.value);
-- 2/2. load tableC
merge into tableC as dest
using tableA as src
on src.id = dest.id
when not matched
then insert (id, value) values( src.id, src.value);
commit;
end;
$$
;
call myprocedure();
select * from tableB;
select * from tableC;
You can get more information on how to write them here: https://docs.snowflake.com/en/developer-guide/snowflake-scripting/index.html
If you want to execute multiple statements, you'll need to run the stored procedure using Snowflake Scripting, JavaScript, Java, or Python.