如何通过休眠

Question

我试图通过hibernate将""的空字符串传递给Date类型列Logout_date：

query.setParameter(3, "");

但抛出异常：

java.lang.String cannot be cast to java.util.Date.

我怎样才能做到这一点。？

修改

String updq2 = "update TblUser a set loggedStatus = ? ,lockedStatus= ?,currentAttempts = ?,logoutDate = ? where upper(a.id)=?";//,lockedStatus= ?, currentAttempts = ?, logoutDate = ? where upper(a.id) = ?";
            Session newSession2=factory.openSession();
            Transaction tx1=newSession2.beginTransaction();
            Query query =newSession2.createQuery(updq2);
            query.setParameter(0, (byte)9);
            query.setParameter(1,"1" );
            query.setParameter(2, 0);
            query.setParameter(3, "");
            query.setParameter(4,  userName.toUpperCase());
query.executeUpdate();
tx1.commit();
newSession2.close();

Answer 1

1. 如果您向数据库和数据库插入数据允许该列的null值，则不要在查询中设置该参数。在这种情况下，它会自动设置为null。

2. 如果你有一个更新声明并希望将现有值设置为null，你可以尝试这样的事情：

   query.setParameter(3, PreparedStatement.setNull());
   

希望有所帮助！

修改

    String updq2;
    bool isNull = false;
    //If your data is null and you want to set it null use this 
    if(yourDate == null)
    {
        updq2 = "update TblUser a set loggedStatus = ? ,lockedStatus= ?,currentAttempts = ?,logoutDate = NULL where upper(a.id)=?";//,lockedStatus= ?, currentAttempts = ?, logoutDate = ? where upper(a.id) = ?";
        isNull = true;
    } //If it isn't null and you want to set and value use this
    else
    {
        updq2 = "update TblUser a set loggedStatus = ? ,lockedStatus= ?,currentAttempts = ?,logoutDate = ? where upper(a.id)=?";//,lockedStatus= ?, currentAttempts = ?, logoutDate = ? where upper(a.id) = ?";

    } 

    Session newSession2=factory.openSession();
    Transaction tx1=newSession2.beginTransaction();
    Query query =newSession2.createQuery(updq2);
    query.setParameter(0, (byte)9);
    query.setParameter(1,"1" );
    query.setParameter(2, 0);

    if(isNull)
    {
         query.setParameter(3,  userName.toUpperCase());
    }
    else
    {
         query.setParameter(3, yourDataHere);
         query.setParameter(4,  userName.toUpperCase());
    }

Answer 2

最佳做法是检查日期是否为空。如果为null，则应避免为date类型的null值添加参数。 Hibernate不会自动将字符串转换为日期。