使用Java在Postgresql中输入Date值

问题描述

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我正在尝试使用java& PostgreSQL。我有一些行日期数据类型。但是我不能使用以下代码添加任何条目到数据库中：

I am trying to program a database application with java & PostgreSQL. I have some rows with date data type. But i cant add any entries to the database with this code :

Date aDate = null;
aDate.setYear(1990);
aDate.setDate(01);
aDate.setMonth(05);

preparedStatement prep = connection.prepareStatement("insert
into exampletable values (?,?);");
prep.setDate(1, (java.sql.Date) aDate);
prep.setDate(2, (java.sql.Date) aDate);

如何在postgreSQL行中添加一个日期，在java中有查询？

How can i add a date in a postgreSQL row with queries in java?

推荐答案

目前还不清楚这是否是您唯一的问题，但这段代码几乎肯定不是你想要的：

It's not clear whether or not this is your only problem, but this code is almost certainly not what you want:

Date aDate = null;
aDate.setYear(1990);
aDate.setDate(01);
aDate.setMonth(05);

• 它会抛出一个 NullPointerException 因为你试图取消引用 null


• 你正在尝试将年份设置为3890AD（ java.util.Date 是基于1900年的多年）


• 然后你将设置月份到6月。如果你以为你把这个月的时间设定到了5月份，那么再考虑一下 - 日期是以0为基础的月份


• 重新使用已被弃用 - 应该为您提供一个大警戒灯


• 然后您尝试将 aDate 转换为 java.sql.Date ，但没有迹象表明它是 a java.sql.Date


• It will throw a NullPointerException because you're trying to dereference null
• You're then trying to set the year to 3890AD (java.util.Date is 1900-based for years)
• You're then setting the month to June. If you thought you were setting the month to May, think again - Date is 0-based for months
• All the methods you're using are deprecated - that should raise a big warning light for you
• You're then trying to cast aDate to java.sql.Date but there's no sign that it is a java.sql.Date

我会建议：



• a href =http://joda-time.sf.net =nofollow> Joda Time 作为一个更好的日期/时间API，或 java.util.Calendar


• 确保在设置值之前实际创建一个实例


• 可能创建一个新的 java .sql.Date 稍后。


• Either use Joda Time as a far better date/time API, or java.util.Calendar
• Make sure you actually create an instance before you set values
• Probably create a new java.sql.Date later on.

例如：

Calendar calendar = Calendar.getInstance();
calendar.set(Calendar.YEAR, 1990);
calendar.set(Calendar.DAY_OF_MONTH, 1);
calendar.set(Calendar.MONTH, 4); // Assuming you wanted May 1st

java.sql.Date date = new java.sql.Date(calendar.getTime().getTime());

// Ideally specify the columns here as well...
PreparedStatement prep = connection.prepareStatement(
    "insert into exampletable values (?,?)");
prep.setDate(1, date);
prep.setDate(2, date);

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