PostgreSQL 影片

Loading...
Google

2008-10-03

Java Type vs PostgreSQL Type (十二) 時間型別之對應 -java.util.Calendar

java.util.Calendar:
在測試Java Type:java.util.Calendar時,先在資料庫建置一張資料表。
資料表語法:
CREATE TABLE calendartypes
(
date date,
"time" time without time zone,
"timestamp" timestamp without time zone,
id serial NOT NULL,
CONSTRAINT datetypes_pkey PRIMARY KEY (id)
)

原始程式碼:
JavaDateType.java:
package zasax.type.timetypes;
import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Calendar;
import zasax.conn.PostgreConnection;
/**
*
* @author YiCheng,Hsiao
*/
public class JavaCalendarType {
private Connection conn;
private PreparedStatement pstmt;
private ResultSet rs;
private String setSQL = "Insert into calendartypes (date,time,timestamp) values (?,?,?)";
private String getSQL = "select * from calendartypes";
public static void main(String[] args)
throws IOException, ClassNotFoundException, SQLException {
JavaCalendarType jct = new JavaCalendarType();
jct.setCalendarValue(Calendar.getInstance(), Calendar.getInstance(), Calendar.getInstance());
ResultSet rs = jct.getCalendarValue();
while (rs.next()) {
System.out.println("Date:" + rs.getDate("date"));
System.out.println("Time:" + rs.getTime("time"));
System.out.println("Timestamp:" + rs.getTimestamp("timestamp"));
}
}
public void setCalendarValue(Calendar c1, Calendar c2, Calendar c3)
throws IOException, ClassNotFoundException, SQLException {
PostgreConnection pc = new PostgreConnection();
this.conn = pc.getConnection();
this.pstmt = conn.prepareStatement(setSQL);
pstmt.setDate(1, new java.sql.Date(c1.getTimeInMillis()));
pstmt.setTime(2, new java.sql.Time(c2.getTimeInMillis()));
pstmt.setTimestamp(3, new java.sql.Timestamp(c3.getTimeInMillis()));
pstmt.execute();
pstmt.close();
conn.close();
}
public ResultSet getCalendarValue()
throws IOException, ClassNotFoundException, SQLException {
PostgreConnection pc = new PostgreConnection();
this.conn = pc.getConnection();
this.pstmt = conn.prepareStatement(getSQL);
this.rs = pstmt.executeQuery();
return rs;
}
}
實際測試程序:
儲存java.util.Calendar的方式:
先透過setCalendarValue(Calendar ,Calendar, Calendar)的方法,將時間引入,再透過java.sql.Date, java.sql.Time, java.sql.Timestamp 等三種容器的承接,才得以透過setDate(), setTime(), setTimestamp() ,存入資料庫。
讀取java.util.Calendar的方式:
由getCalendarValue()的方法,以SQL 查詢語法"select * from calendartype ",經executeQuery()回傳至ResultSet,再經由ResultSet的方法getDate(), getTime(), getTimestamp() ,讀取內容。
印出結果如下:
整理表格如下:
Java Types PostgreSQL Types 特性
java.util.Calendar date 4 bytes,只用於日期
time 8 bytes,只用於一日內時間
timestamp 8 bytes,包括日期和時間

備註:
java.sql.Date, java.sql.Time, java.sql.Timestamp, 雖然也都是跟時間有關的型別,而這三個型別較屬於為容器系統,為了便於跟資料庫的型別存取讀取。

Java Types 自己產生時間 存入PostgreSQL資料庫的對應型別
java.util.Date T 需要轉譯
java.util.Calendar T 需要轉譯
java.sql.Date F date
java.sql.Time F time
java.sql.Timestamp F timestamp

沒有留言:

網誌存檔

PostgreSQL & Google-Analytics Running...

::Planet PostgreSQL::

PostgreSQL Information Page

PostgreSQL日記(日本 石井達夫先生Blog)

PostgreSQL News

黑喵的家 - 資料庫相關

Google 網上論壇
PostgreSQL 8 DBA 專業指南中文版
書籍內容討論與更多下載區(造訪此群組)
目錄下載: PostgreSQL_8 _DBA_Index_zh_TW.pdf (更新:2007-05-18)

全球訪客分佈圖(Google)

全球訪客分佈圖(Google)