Question

eclipse中写jsp文件，提示加载驱动和连接数据库都正常，但查询数据库时不能查询，求解答，万分感谢

try {
s = con.createStatement();
String sql = "SELECT * FROM" + tableName;
rs = s.executeQuery(sql);
while (rs.next()) {

out.println("<tr>");
out.println("<td>" + rs.getInt("id") + "</td>");
out.println("<td>" + rs.getString("name") + "</td>");
out.println("<td>" + rs.getString("city") + "</td>");
out.println("<td>" + rs.getInt("price") + "</td>");
out.println("<td>" + rs.getInt("number") + "</td>");
out.println("<td>" + rs.getString("picture") + "</td>");
out.println("</tr>");
}
rs.close();
s.close();
con.close();

} catch (SQLException e) {
System.out.println("不能执行查询");
}
%>
查询部分的代码

Answer 1

package com.vince.jdbc;

import static com.vince.jdbc.JdbcDemo.PASSWORD;
import static com.vince.jdbc.JdbcDemo.URL;
import static com.vince.jdbc.JdbcDemo.USERNAME;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
*
* @author Administrator
*/
public class JdbcQueryDemo {
//数据库连接地址

public final static String URL = "jdbc:mysql://localhost:3306/test";
//用户名
public final static String USERNAME = "root";
//用户密码
public final static String PASSWORD = "123456";
//驱动
public final static String DRIVER = "com.mysql.jdbc.Driver";

public static void query() {
try {
//1、加载数据库驱动程序
Class.forName(DRIVER);
//2、获取数据库连接
Connection conn = DriverManager.getConnection(URL, USERNAME, PASSWORD);
//3、构造查询的sql语句

String sql = "select id,name,age,description from person";
//4、构造一个Statement实例,用来发生SQL语句的载体
Statement state = conn.createStatement();
//5、执行查询sql语句，并返回结果
ResultSet rs = state.executeQuery(sql);
//6、处理结果
while (rs.next()) {
// rs.getInt("id");
int id = rs.getInt(1);
String name = rs.getString(2);
int age = rs.getInt(3);
String description = rs.getString(4);
System.out.println("id=" + id + ",name" + name + ",age" + age + ",description" + description);
}
//7、关闭连接(释放资源)
rs.close();
state.close();
conn.close();

System.out.println("success!");
} catch (ClassNotFoundException | SQLException ex) {
Logger.getLogger(JdbcDemo.class.getName()).log(Level.SEVERE, null, ex);
}
}
public static void main(String[] args) {
query();
System.out.println("success!!!");
}
}
用这个试试，你先查一个表试试（具体的表）String sql = "SELECT * FROM 表名";

老师讲用*——是不推荐的……