MySQL Insert Records from Multiple Tables to New Table

Question

I'm trying to populate a new table with records from 2 other tables.

period_states is new/empty

 period_states
   id
   period_id
   sla_id

periods - contains 15 records

periods
  id

slas - contains 84 records

slas
  id

I need to populate period_states with each existing sla_id having each exiting period_id. So, ultimately there should be 1260 records in period_states.

Any idea how to automate this? It would be a nightmare to populate manually...

Thank you in advance!!

Answer 1

If the id column of period states is defined as AUTO_INCREMENT, then this should work:

INSERT INTO period_states (period_id, sla_id)
SELECT p.id AS period_id
     , s.id AS sla_id
  FROM periods p
 CROSS
  JOIN slas s

And here's an example of one way to supply a value for the id column:

INSERT INTO period_states (id, period_id, sla_id)
SELECT @myid := @myid + 1 AS id
     , p.id AS period_id
     , s.id AS sla_id
  FROM periods p
 CROSS
  JOIN slas s
 CROSS
  JOIN (SELECT @myid := 0) m

Answer 2

INSERT INTO period_states
(period_id, sla_id)
SELECT periods.id, slas.id
FROM periods
CROSS JOIN slas