JAVA JDBC 连接Mysql 更新数据 双表查询更新

package com.test.json;

package com.test.javahome;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;

public class DataBaseTest {
private static final String TABLE_01 = "dizhi2";
private static final String TABLE_02 = "real_480";
public static Connection getConnection() throws SQLException, java.lang.ClassNotFoundException {
// 第一步：加载MySQL的JDBC的驱动
Class.forName("com.mysql.jdbc.Driver");

// 取得连接的url,能访问MySQL数据库的用户名,密码；studentinfo：数据库名
String url = "jdbc:mysql://localhost:3306/wumigen";
String username = "root";
String password = "qwert";

// 第二步：创建与MySQL数据库的连接类的实例
System.out.println("main ==============begin2");
Connection con = DriverManager.getConnection(url, username, password);
System.out.println("main ==============begin3");
return con;
}

public static void main(String args[]) {
try {
System.out.println("main ==============begin");
Connection con = getConnection();
System.out.println("main ==============begin4");
Statement sql_statement = con.createStatement();
String query1 = "select * from "+TABLE_01;
String query2 = "select * from "+TABLE_02;
System.out.println("query1 ==============begin");
ResultSet result = sql_statement.executeQuery(query1);
ArrayList<px> pxlist = new ArrayList<px>();
while (result.next()) {
PX p1 = new PX();
p1.type = result.getString(2);
p1.number = result.getString(3);
p1.img_320 = result.getString(4);
pxlist.add(p1);
}
System.out.println("query1 ==============end, size = " + pxlist.size());
System.out.println("query2 ==============begin");
ResultSet result2 = sql_statement.executeQuery(query2);
ArrayList<py> pylist = new ArrayList<py>();
while (result2.next()) {
PY p2 = new PY();
p2.number = result2.getString(2);
p2.img_480 = result2.getString(3);
pylist.add(p2);
}
for (int i = 0; i < pxlist.size(); i++) {
for (int j = 0; j < pylist.size(); j++) {
if (pylist.get(j).number == pxlist.get(i).number) {
pxlist.get(i).img_480 = pylist.get(j).img_480;
}
}

if (pxlist.get(i).img_320.length() == 0) {
System.out.println("=========null " + pxlist.get(i).number);
} else {
String updateSql = "update "+TABLE_01+" set img_480='" + pxlist.get(i).img_480+
"' where number='"+ pxlist.get(i).number + "'";
System.out.println("begin to update ==> "+i);
sql_statement.execute(updateSql);
}
}
System.out.println("query2 ==============end, size = " + pylist.size());
sql_statement.close();
con.close();
System.out.println("=========end ");
} catch (java.lang.ClassNotFoundException e) {
System.err.print("ClassNotFoundException");
System.err.println(e.getMessage());
} catch (SQLException ex) {
ex.printStackTrace();
System.err.println("SQLException: " + ex.getMessage());
}
}
}

class PX {
String type;

String number;

String img_320;

String img_480;
}

class PY {
String number;

String img_480;
}

</py></py></px></px>