MySQL5指定时间段查询问题（已解决）

MySQL5指定时间段查询问题（已解决）

 

今天在做数据分发同步工具的时候遇到了点问题，MySQL5按照字段的时间段范围查询不能成功的问题。

 

现在问题还没有解决，下面是我专门为了一个低级的查询写了个JDBC测试，连接池什么的统统不要，将问题的范围尽量缩小。

 

原因是PreparedStatement设置java.sql.Date参数没有被认为传递的是合法的Date，而查询不到数据。如果你不用JDBC、不用PreparedStatement，你是发现不到这个问题的。

 

一、环境

MySQL5.1.30

Java 1.5

 

 

SQL脚本

CREATE TABLE genreparam (                        
                            genre_id int(11) NOT NULL,                    
                            updatenum bigint(20) DEFAULT '0',    
                            ishd bigint(1) DEFAULT NULL,                
                            kind bigint(20) DEFAULT NULL,            
                            clicks bigint(20) DEFAULT '0',            
                            create_time datetime NOT NULL,            
                            update_time datetime NOT NULL,            
                             PRIMARY KEY (genre_id)                            
                        ) ENGINE=MyISAM DEFAULT CHARSET=utf8        

 

 

二、测试

 

要求传递两个参数，用来控制update_time字段的范围，查询数据库记录。

 

测试代码：

import java.sql.*;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.List;

public class TestJDBC {
         private static final String genreparam_sql = "" +
                         "select genre_id, updatenum, ishd, kind, clicks, create_time, update_time\n" +
                         "    from genreparam\n" +
                         " where update_time BETWEEN ? AND ? \n" +
                         " limit ?," + 300;

         private static final String genreparam1_sql = "" +
                         "select genre_id, updatenum, ishd, kind, clicks, create_time, update_time\n" +
                         "    from genreparam\n" +
                         " where DATE_FORMAT(update_time, '%Y-%c-%e %T') BETWEEN ? AND ? \n" +
                         " limit ?," + 300;

         public static void main(String[] args) throws SQLException, ClassNotFoundException {
                Class.forName( "com.mysql.jdbc.Driver");
                String user = "vcom";
                String pswd = "vcom";
                String dburl = "jdbc:mysql://192.168.104.163:3306/VOD3_01";
                Connection conn = DriverManager.getConnection(dburl, user, pswd);
                System.out.println(conn == null);

//                List<Genreparam> genList = new ArrayList<Genreparam>();
                Calendar c = Calendar.getInstance();
                c.set(1900, 1, 1);
                Date _start = new Date(c.getTimeInMillis());
                Date _end = new Date(System.currentTimeMillis());
                System.out.println(_start);
                System.out.println(_end);
                PreparedStatement pstmt = conn.prepareStatement(genreparam1_sql);
                pstmt.setDate(1, _start);
                pstmt.setDate(2, _end);
                pstmt.setString(1, "1900-2-1 00:00:00");
                pstmt.setString(2, "2010-2-1 00:00:00");
                pstmt.setInt(3, 0);
                ResultSet rs = pstmt.executeQuery();
                int i = 0;
                while (rs.next()) {
//                        Genreparam genreparam = new Genreparam();
//                        genreparam.setGenre_id(rs.getLong("genre_id"));
//                        genreparam.setUpdatenum(rs.getLong("updatenum"));
//                        genreparam.setIshd(rs.getInt("ishd"));
//                        genreparam.setKind(rs.getInt("kind"));
//                        genreparam.setClicks(rs.getLong("clicks"));
//                        genreparam.setCreate_time(rs.getDate("create_time"));
//                        genreparam.setUpdate_time(rs.getDate("update_time"));
//                        genList.add(genreparam);
                        i++;
                }
                rs.close();
                conn.close();
                System.out.println("查询记录总数为:" + i);
        }
}

 

传递java.sql.Date参数总查不到数据，于是修改为传递字符串，才勉强获取到了。。

 

false
1900-02-01
2009-07-31
查询记录总数为:4

Process finished with exit code 0

 

写SQL查：

SELECT *
     FROM genreparam
WHERE DATE_FORMAT(update_time, '%Y-%c-%e %T') BETWEEN '1900-2-1 00:00:00' AND     '2010-2-5 00:00:00'

查询了4条记录。

 

三、思考与解决

 

究竟是什么原因呢，日期不能直接做大小比较吗？

最终发现，MySQL对日期的比较直接可以用字符串来比较，比如：

select genre_id, updatenum, ishd, kind, clicks, create_time, update_time
     from genreparam
where update_time < '2010-2-1 00:00:00 '

虽然， '2010-2-1 00:00:00 '不是日期类型，但仍然可以做比较。

 

下面看看如果将字符串转为日期呢，能否比较呢？

select genre_id, updatenum, ishd, kind, clicks, create_time, update_time
     from genreparam
where update_time < TIMESTAMP( '2010-2-1 00:00:00 ')

执行结果依然正确。

 

这就非常让人迷惑了，为什么不能直接传递一个java.sql.Date参数就挂了呢？

在此，实在很无奈，就写个格式化方法吧，将Date参数改为传String参数就可以了。

         private static final String data_format = "yyyy-MM-dd kk:mm:ss";

         public static String data2ISOString(java.util.Date date) {
                SimpleDateFormat sf = new SimpleDateFormat(data_format);
                 return sf.format(date);
        }

 

这样，问题就彻底得到解决了。