Question

拜请高人，看到请进！！！ 用eclipse 连接到oracle数据库时，怎么获得数据库表中的记录数：代码如下：

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.RowId;
import java.sql.SQLException;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

public class JDBCReadDemo01{

public static void main(String[] args) throws Exception{

String sql = "select count(*) from registry";
Class.forName("oracle.jdbc.driver.OracleDriver"); //加载驱动
Connection conn = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:orcl","qqserver","qq"); //连接到服务器

// PreparedStatement pstmt = conn.prepareStatement(sql,ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_READ_ONLY);
PreparedStatement pstmt = conn.prepareStatement(sql);
ResultSet rs = pstmt.executeQuery(); //查询操作

System.out.println("表中记录数数："+ xxxx);

conn.close(); //关闭数据库
}

};

怎么获得registry表中的记录数啊？？？？？？？？？？？？？？？？？？？？

Answer 1

package dao;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class BaseDao {
static Connection con;
static PreparedStatement ps;
static ResultSet rs;

public static Connection Connect() {
try {
String name = "qqserver";
String pwd = "qq";
Class.forName("oracle.jdbc.driver.OracleDriver");
con = DriverManager.getConnection(
"jdbc:oracle:thin:@localhost:1521:orcl", name, pwd);
} catch (SQLException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
return con;
}

public static void CloseConnect() {
if (con != null) {
try {
con.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if (ps != null) {
try {
ps.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if (rs != null) {
try {
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
}

}

}

一个程序员请注意规范 这是可以成功的 我试过

追问

让帮忙解决问题呢，你所答非所问吧？！注意抓住问题的要点去解决问题！

追答

规范本来就不应该把连接数据库和代码写在一起啊 代码是吧

/**
* 查询所有
*/
public List Userall() {
con = BaseDao.Connect();
List list = new ArrayList();
try {
String sql = "select * from user";
ps = con.prepareStatement(sql);
rs = ps.executeQuery();
while (rs.next()) {
User us = new User();
us.setId(rs.getInt("id"));
us.setName(rs.getString("name"));
us.setPwd(rs.getString("pwd"));
us.setSex(rs.getString("sex"));
list.add(us);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
BaseDao.CloseConnect();
}
return list;
}

Answer 2

while(rs.next()){
int empno=rs.getInt(1);
String ename=rs.getString(2);
String job=rs.getString(3);
java.util.Date hiredate=rs.getDate(4);
float sal=rs.getFloat(5);
float comm=rs.getFloat(6);

Result中是按行读取数据的 然后再按列读取数据--->rs.getXXX(1)这就是读取该行第几列的数据，注意是从1开始的 具体可以去查java api文档
希望可以帮上你

追问

不行啊，试过了

Answer 3

String sql="select count(*) as count from registry";
while(rs.next()) //这里rs是false 最后什么都输出不出来
{
System.out.println(rs.getString("count") );
}