Question

String datum = datumInvoer.getText();

    **String bdate = bdatumInvoer.getText();**

    String[] speler = spelers.getSelectedItem().toString().split(" ");


    String[] toernooi = toernooien.getSelectedItem().toString().split(" ");
    try {
        PreparedStatement query = con.prepareStatement("INSERT INTO `fullhouse`.`inschrijving_toernooi` ( `IT_datum`, `IT_betaaldatum`, `speler`, `toernooi`) VALUES (?, ?, ? ,?)");
        query.setString(1, datum);
        query.setString(2, bdatum);
        query.setString(3, speler[0]);
        query.setString(4, toernooi[0]);

        query.execute();

i have set the default to NULL , but it still wont insert it i am close to changing the datatype to varchar.

ERROR: incorrect date value

delimiter $$

CREATE TABLE `inschrijving_toernooi` (
  `IT_code` int(11) NOT NULL AUTO_INCREMENT,
 `IT_datum` date DEFAULT NULL,
  `IT_betaaldatum` date DEFAULT NULL,
 `speler` int(11) NOT NULL,
 `toernooi` int(11) NOT NULL,
PRIMARY KEY (`IT_code`),
UNIQUE KEY `aaa` (`speler`,`toernooi`),
 KEY `FS_code_idx` (`speler`),
KEY `FT_code_idx` (`toernooi`),

Answer 1

First Convert your date parameter from string to date. For that follow code below.

String bdate = bdatumInvoer.getText();
// get the correct date Format
// follow the link to get correct date format
// throws ParseException 
Date date = new SimpleDateFormat("dd-MM-yyyy").parse(bdate);

Class SimpleDateFormat API

Now in prepared statement set them as date like shown below. As your table structure allows date in table.

query.setDate(2, date);

Now you still want to set null to that column then you can use and tell your query to set null by using following format in prepared statement.

query.setNull(2, java.sql.Types.DATE);

OR

query.setDate(2, null);

setNull API

Mapping of java.sql.Types to SQL types

I think this will solve your issue.