hibernate not generate auto increment constraint on mysql table

Question

I have been searching through different forums for information and I have tried different solutions, but I'm still unable to correct my issue.

I am using hibernate4 annotations for mapping my entities. Auto increment key is not detected when tables are created using hibernate in mysql.

I have the following code:

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(unique = true, nullable = false)
private int responseId;

I have also tried:

@Id
@GenericGenerator(name="generator", strategy="increment")
@GeneratedValue(generator="generator")
private int responseId;

With hibernate the id is automatically assigned to a row, but in the mysql table it has no AutoIncrement Constraint. I have to mark field as AI manually. This becomes problematic when I manually insert a record for testing or use jdbc statements for the table. Please let me know what I am missing in configuration that is preventing the hibernate id from assigning an AutoIncrement Contraint.

Answer 1

Use the IDENTITY generator, and use the columnDefinition attribute of @Column to specify the type of the column:

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(columnDefinition = "MEDIUMINT NOT NULL AUTO_INCREMENT")
private int responseId;