Incorrect integer value: '' for column 'id' at row 1

To let MySQL generate sequence numbers for an AUTO_INCREMENT field you have three options:

1. specify list a column list and omit your auto_incremented column from it as njk suggested. That would be the best approach. See comments.
2. explicitly assign NULL
3. explicitly assign 0

3.6.9. Using AUTO_INCREMENT:

...No value was specified for the AUTO_INCREMENT column, so MySQL assigned sequence numbers automatically. You can also explicitly assign NULL or 0 to the column to generate sequence numbers.

These three statements will produce the same result:

INSERT INTO workorders (`priority`, `request_type`) VALUES(?, ?, ...)
INSERT INTO workorders VALUES(NULL, ?, ...)
INSERT INTO workorders VALUES(0, ?, ...)

That probably means that your id is an AUTO_INCREMENT integer and you're trying to send a string. You should specify a column list and omit it from your INSERT.

INSERT INTO workorders (column1, column2) VALUES (?, ?)