Update according to a condition

Question

how do i update a table according to a condition (i.e. dynamically update).
I have a table which i need to insert a new record for each customer if they have purchased a specific item before.
my purchase table has the following columns (id, cust id, purchase id, date).
how do i insert a new record (sequence id, cust_id, 55, today) for every customer if they have a record in my purchase table with a purchase_id=54?

Answer 1

how do i update a table according to a ....
how do i insert a new record Confusing requirement....
Though from whatever I understand, you want following
INSERT INTO <TABLE_NAME>
      SELECT sequence id, cust_id, 55, SYSDATE
      FROM purchase_table
      WHERE purchase_id = 54 ;