Please try the below command:
sqoop job -create retaildb_comercia -- import --connect jdbc:mysql://mysqldb.edu.cloudlab.com/retail_db --username labuser --P --table comercia --target-dir sayni_sqoop --check-column customer_id --incremental append --last-value 12436 -m 1
There needs to be a space between -- and import. Also, I am attaching a documentation for sqoop job.