数据库行锁实验二，两个同表删除操作不存在交集而不会死锁

删除程序一：删除id=1的记录

package com.hy.multidelete;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;

import org.apache.log4j.Logger;

public class Deleter {
    private static Logger log = Logger.getLogger(Deleter.class);
    
    public void doDelete() {
        Connection conn = null;
        Statement stmt = null;
        
        try{
            Class.forName(DBParam.Driver).newInstance();
            conn = DriverManager.getConnection(DBParam.DbUrl, DBParam.User, DBParam.Pswd);
            conn.setAutoCommit(false);
            stmt = conn.createStatement();
            
            String sql="delete from TestTB17 where id=1";
            int deleted=stmt.executeUpdate(sql);
            
            // 在此处停住断点，另一个删除程序CleanExpiredMocker会执行不下去
            log.info("Deleter deleted "+deleted+" records.");
            
            // 直到接下来回滚或提交CleanExpiredMocker才可以执行
            conn.rollback();
            log.info("Rollbacked.");
        } catch (Exception e) {
            System.out.print(e.getMessage());
        } finally {
            try {
                stmt.close();
                conn.close();
            } catch (SQLException e) {
                System.out.print("Can't close stmt/conn because of " + e.getMessage());
            }
        }
    }
    
    public static void main(String[] args) {
        Deleter d=new Deleter();
        d.doDelete();
    }
}

删除程序二：删除id>250的记录，由于与第一个程序不存在交集，因此不会受行锁的影响，无论第一个程序是否提交回滚都会正常运行。

package com.hy.multidelete;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;

import org.apache.log4j.Logger;

public class CleanExpiredMocker {
    private static Logger log = Logger.getLogger(CleanExpiredMocker.class);
    
    public void doClean() {
        Connection conn = null;
        Statement stmt = null;
        
        try{
            Class.forName(DBParam.Driver).newInstance();
            conn = DriverManager.getConnection(DBParam.DbUrl, DBParam.User, DBParam.Pswd);
            stmt = conn.createStatement();
            
            String sql="delete from TestTB17 where id>250";
            int deleted=stmt.executeUpdate(sql);
            log.info("CleanExpiredMocker deleted "+deleted+" records.");;    
        } catch (Exception e) {
            System.out.print(e.getMessage());
        } finally {
            try {
                stmt.close();
                conn.close();
            } catch (SQLException e) {
                System.out.print("Can't close stmt/conn because of " + e.getMessage());
            }
        }
    }
    
    public static void main(String[] args) {
        CleanExpiredMocker c=new CleanExpiredMocker();
        c.doClean();
    }
}

完整程序下载（拿下去请自行修改sql语句）： https://files.cnblogs.com/files/xiandedanteng/multidelete20191128.rar

--END-- 2019年11月28日22:13:22