Running transact SQL (t-sql) block in python using pyodbc

Question

I have the below set of T-SQL statements. Where a cursor is loaded with about 500 IDs. And for each ID a set up update statements are executed.

    declare @id int
    declare @ids cursor

    set @ids=cursor fast_forward read_only for
    select id from table_id;

    open @ids
    fetch next from @ids into @id
    while @@FETCH_STATUS=0
    begin
        update table2 set qty2=0 where id=@id;
        update table3 set qty3=0 where id=@id;
        fetch next from @ids into @id
    end

    close @ids
    deallocate @ids

When I run this using pyodbc in python by setting autocommit=True, the update statements for only a few IDs are run, but not for every ID. Why is that behavior?

Here is the python statement used.

tsqlString = "declare @id int ... deallocate @ids"
con = pyodbc.connect(connection_string, autocommit=True))
cursor = con.cursor()
cursor.execute(tsqlString)

cursor.close()
con.close()