title: How to apply unique constraints using annotation
body: <pre><code>@Column(name = "userId")
      @UniqueConstraint
      private Integer userId;
  </code></pre>
  
  <p>I am using these annotation for entering data into database table.
  i want to make userId field unique field. but when i am doing like it it is showing me error <code>@UniqueConstraints is disallowed for this location.</code></p>