[hibernate-users] Question about annotations

hello, i am new to hibernate, so please grant me some questions. My hibernate session uses the MySQLDialect. 1. Empty fields in the Model are not NULL in db. My definition: @Size(max = 50) private String title; In the db is later an empty string, the @NotNull annotation also is not working because its an emptry String "" 2. Unique fields are not working? @Email @Column(unique = true) @Size(min = 7, max = 50) private String email; The email field should be unique in database, but it is not. And in the structure of the table also not defined as unique. Someone can give me a clue please? TIA Daniel