如何使用 JDBC 程序在数据库中插入 Timestamp 值?
SQL 中的 Timestamp 数据类型类似于 Date(在 SQL 中),两者都存储日:月:年:时:分:秒。此外,Timestamp 还存储小数秒。
将 Timestamp 插入数据库
PreparedStatement 接口提供了一个名为 setTimestamp() 的方法,该方法接受两个参数:一个整数变量,表示需要存储时间戳的占位符的参数索引;以及一个长整型变量,表示从纪元时间(标准基准时间,即 1970 年 1 月 1 日 00:00:00 GMT)到所需时间的毫秒数。
示例
假设我们在数据库中有一个名为 dispatches 的表,其描述如下:
+------------------+--------------+------+-----+-------------------+ | Field | Type | Null | Key | Default | +------------------+--------------+------+-----+-------------------+ | Product_Name | varchar(100) | YES | | NULL | | Name_Of_Customer | varchar(100) | YES | | NULL | | Time_Of_Dispatch | timestamp | NO | | CURRENT_TIMESTAMP | | Location | varchar(100) | YES | | NULL | +------------------+--------------+------+-----+-------------------+
如您所见,此表包含一个名为 Time_Of_Dispatch 的列,用于存储时间戳值。
我们可以使用 PreparedStatement 接口的 setTimestamp() 方法将时间戳存储到其中,并使用 ResultSet 接口的 getTimestamp() 方法检索它。
以下 JDBC 程序将记录存储到 dispatches 表中并检索它们:
import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.Statement; import java.sql.Timestamp; public class TimeStampExample { public static void main(String args[])throws Exception { //Getting the connection String mysqlUrl = "jdbc:mysql://127.0.0.1/sampledb"; Connection con = DriverManager.getConnection(mysqlUrl, "root", "password"); System.out.println("Connection established......"); //Inserting values to a table String query = "INSERT INTO Dispatches VALUES (?, ?, ?, ?)"; PreparedStatement pstmt = con.prepareStatement(query); pstmt.setString(1, "KeyBoard"); pstmt.setString(2, "Amith"); pstmt.setTimestamp(3, new Timestamp(1567296000000L)); pstmt.setString(4, "Hyderabad"); pstmt.execute(); pstmt.setString(1, "Earphones"); pstmt.setString(2, "Sumith"); pstmt.setTimestamp(3, new Timestamp(1556668800000L)); pstmt.setString(4, "Vishakhapatnam"); pstmt.execute(); pstmt.setString(1, "Mouse"); pstmt.setString(2, "Sudha"); pstmt.setTimestamp(3, new Timestamp(1551398399000L)); pstmt.setString(4, "Vijayawada"); pstmt.execute(); System.out.println("Records inserted......"); //Creating Statement object Statement stmt = con.createStatement(); ResultSet rs = stmt.executeQuery("select * from Dispatches"); //Retrieving values while(rs.next()) { System.out.println("Product Name: "+rs.getString("Product_Name")); System.out.println("Name Of The Customer: "+rs.getString("Name_Of_Customer")); System.out.println("Time Of Dispatch: "+rs.getTimestamp("Time_Of_Dispatch")); System.out.println("Location: "+rs.getString("Location")); System.out.println(); } } }
输出
Connection established...... Records inserted...... Product Name: KeyBoard Name Of The Customer: Amith Time Of Dispatch: 2019-09-01 05:30:00.0 Location: Hyderabad Product Name: Earphones Name Of The Customer: Sumith Time Of Dispatch: 2019-05-01 05:30:00.0 Location: Vishakhapatnam Product Name: Mouse Name Of The Customer: Sudha Time Of Dispatch: 2019-03-01 05:29:59.0 Location: Vijayawada
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