课时6：PrepareStatement语句

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1.PreparedStatement为预定义语句，继承Statement。

2.Statement只能静态操作SQL语句，如果要想动态操作SQL语句又该如何实现呢？例如：注册会员，这里可以使用PreparedStatement来动态操作SQL语句，PreparedStatement通过使用占位符“？”，来预生成SQL语句，从而达到动态操作的功能

3.实例

3.1

面向对象，就是尽量把对象定义成一个java文件，所有属性和操作都定义到里面。在其他函数中直接创建对象和调用对象

package com.geek99.demo;

import java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

public class Test4 {

public static void main(String[] args) {

// insert("tom1","tom1@111111.com");

// Customer c = new Customer();

// c.setName("rose");

// c.setEmail("rose@1111.com");

// insert(c);

// c.setId(1);

// c.setName("dsfasdfa");

// update(c);

// del(2);

Customer c=query(3);

if(c!=null)

System.out.println(c.getName()+":"+c.getEmail());

}

static void insert(String name, String email) {

Connection conn = DBUtil.open();

String sql = "insert into CustomerTbl(name,email)values(?,?)";

try {

PreparedStatement pstmt = conn.prepareStatement(sql);

pstmt.setString(1, name);

pstmt.setString(2, email);

pstmt.executeUpdate();

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

static void insert(Customer c) {

Connection conn = DBUtil.open();

String sql = "insert into CustomerTbl(name,email)values(?,?)";

try {

PreparedStatement pstmt = conn.prepareStatement(sql);

pstmt.setString(1, c.getName());

pstmt.setString(2, c.getEmail());

pstmt.executeUpdate();

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

static void update(Customer c) {

Connection conn = DBUtil.open();

String sql = "update CustomerTbl set name=? where id=?";

try {

PreparedStatement pstmt = conn.prepareStatement(sql);

pstmt.setString(1, c.getName());

pstmt.setInt(2, c.getId());

pstmt.executeUpdate();

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

static void del(int id) {

Connection conn = DBUtil.open();

String sql = "delete from CustomerTbl where id=?";

try {

PreparedStatement pstmt = conn.prepareStatement(sql);

pstmt.setInt(1, id);

pstmt.executeUpdate();

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

static Customer query(int id) {

Connection conn = DBUtil.open();

String sql = "select id,name,email from CustomerTbl where id=?";

try {

PreparedStatement pstmt = conn.prepareStatement(sql);

pstmt.setInt(1, id);

ResultSet rs=pstmt.executeQuery();

// pstmt.executeUpdate();

if(rs.next()){

String name=rs.getString(2);

String email=rs.getString(3);

Customer c=new Customer();

c.setId(id);

c.setName(name);

c.setEmail(email);

return c;

}

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

return null;

}

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