修改UserFavorite表和UsrStar实体类

Change-Id: I0b535cf4c8efd35e74df69ec3c1f8a4b2f0b8eed
diff --git a/src/main/java/entity/UserStar.java b/src/main/java/entity/UserStar.java
index c47ec24..d39a488 100644
--- a/src/main/java/entity/UserStar.java
+++ b/src/main/java/entity/UserStar.java
@@ -1,5 +1,6 @@
 package entity;
 
+import java.util.Date;
 import javax.persistence.Column;
 import javax.persistence.Entity;
 import javax.persistence.ForeignKey;
@@ -8,6 +9,8 @@
 import javax.persistence.JoinColumn;
 import javax.persistence.ManyToOne;
 import javax.persistence.Table;
+import javax.persistence.Temporal;
+import javax.persistence.TemporalType;
 
 @Entity
 @Table(name = "UserFavorite")
@@ -39,5 +42,9 @@
     )
     public Seed seed;
 
+    @Column(name = "created_at", nullable = false)
+    @Temporal(TemporalType.TIMESTAMP)
+    public Date createdAt;
+
     public UserStar() {}
 }
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