Best way to avoid duplicate entry into mysql database

Question

I have a table with 3 columns - id (pk), pageId (fk), name. I have a php script which dumps about 5000 records into the table, with about half being duplicates, with same pa

Answer 1

First step would be to set a unique key on the table:

ALTER TABLE thetable ADD UNIQUE INDEX(pageid, name);

Then you have to decide what you want to do when there's a duplicate. Should you:

1. ignore it?

   INSERT IGNORE INTO thetable (pageid, name) VALUES (1, "foo"), (1, "foo");
   

2. Overwrite the previously entered record?

   INSERT INTO thetable (pageid, name, somefield)
   VALUES (1, "foo", "first")
   ON DUPLICATE KEY UPDATE (somefield = 'first')
   
   INSERT INTO thetable (pageid, name, somefield)
   VALUES (1, "foo", "second")
   ON DUPLICATE KEY UPDATE (somefield = 'second')
   

3. Update some counter?

   INSERT INTO thetable (pageid, name)
   VALUES (1, "foo"), (1, "foo")
   ON DUPLICATE KEY UPDATE (pagecount = pagecount + 1)