Question

I have a form and a database table named reports. I have a date field (primary key) and a textarea named changes to say what’s been changed on that date. If the date is the same I want to be able to overwrite the information in the ‘changes’ column for that date.

My insert command, which works on its own, is as follows:

mysql_query("
  INSERT INTO reports (thedate,changes)
    VALUES ('$_POST[thedate]','$_POST[changes]')
");

I understand that I’ll need to use ON DUPLICATE KEY UPDATE after my INSERT but after numerous attempts I cannot get it right. Not only do things no update but it seems to break my insert command so even a new row isn’t added to the database.

Apologies if this is a duplicate question. After lots of searching and lots of trying I cannot get it to work.

Answer 1

Have a look att REPLACE.

REPLACE works exactly like INSERT, except that if an old row in the
table has the same value as a new row for a PRIMARY KEY or a UNIQUE
index, the old row is deleted before the new row is inserted.

Note that if you have a foreign key with an action ON DELETE it will be triggered when using REPLACE since it does a delete followed by an insert .

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Using ON DUPLICATE KEY it could look like this:

INSERT reports (thedate, changes) VALUES ('$_POST[thedate]', '$_POST[changes]')
  ON DUPLICATE KEY UPDATE changes = '$_POST[changes]'