Question

I’m developping an application in JSF 2.0, as DBMS I’m using MySQL.
I’m having an issue with the INSERT … ON DUPLICATE KEY UPDATE statement, it generates a new primary key every time a row gets updated. This is the query I’m using.

INSERT INTO aanwezigheid_i (jongereId, datum, aanwezig, aankomstTijd, vertrekTijd, alternatiefKamp, redenAfwezig)
VALUES (?,?,?,?,?,?,?)
ON DUPLICATE KEY
UPDATE aanwezig = ?, aankomstTijd = ?, vertrekTijd = ?, alternatiefKamp = ?, redenAfwezig = ?

The table ‘aanwezigheid_i’ has got the following columns:

aanwezigheidId (INT(11), PRIMARY KEY)| jongereId| datum| aanwezig| aankomstTijd| vertrekTijd| alternatiefKamp| redenAfwezig

If I insert a first row, the primary key ‘aanwezigheidId’ has got the value 1.
If I UPDATE this first row 10 times and insert a second row afterwards, the primary key value of the second row is 12 and not 2. What am I doing wrong?
Any help would be appreciated.

Answer 1

You’re not sending aanwezigheidId – the primary key – into the INSERT, that’s why a new row is created. The ON DUPLICATE KEY UPDATE clause only takes effect when a record with existing key is inserted.