JDBC之——PreparedStatement实现对数据库的增删改操作

SQL入门：理解关系型数据库，掌握SELECT语句，会使用SQLAlchemy或JDBC #生活技巧# #工作学习技巧# #编程语言学习路径#

一、PreparedStatement接口引入

PreparedStatement是Statement的子接口，属于预处理操作，与直接使用Statement不同的是，PreparedStatement在操作时，是现在数据表中准备好了一条SQL语句，但是此SQL语句的具体内容暂时不设置，二十之后再进行设置。

（以后开发一部用PreparedStatement，不用Statement）

二、使用PreparedStatement接口实现添加数据操作

public class DbUtil {

private static String dbUrl="jdbc:mysql://localhost:3306/db_book";

private static String dbUserName="root";

private static String dbPassword="root";

private static String jdbcName="com.mysql.jdbc.Driver";

public Connection getCon() throws Exception {

Class.forName(jdbcName);

Connection con = DriverManager.getConnection(dbUrl, dbUserName, dbPassword);

return con;

}

public void close(Statement stmt,Connection con) throws Exception {

if(stmt!=null) {

stmt.close();

}

if(con!=null) {

con.close();

}

}

}

public class Book {

private int id;

private String bookName;

private float price;

private String author;

private int bookTypeId;

public Book(String bookName, float price, String author, int bookTypeId) {

super();

this.bookName = bookName;

this.price = price;

this.author = author;

this.bookTypeId = bookTypeId;

}

public Book(int id, String bookName, float price, String author, int bookTypeId) {

super();

this.id = id;

this.bookName = bookName;

this.price = price;

this.author = author;

this.bookTypeId = bookTypeId;

}

}

public class Demo01{

private static DbUtil dbUtil = new DbUtil();

private static int addBook(Book book)throws Exception{

Connection con = dbUtil.getCon();

String sql = "insert into t_book values(null,?,?,?,?)";

PreparedStatement pstmt = con.prepareStatement(sql);

pstmt.setString(1, book.getBookName());

pstmt.setFloat(2, book.getPrice());

pstmt.setString(3, book.getAuthor());

pstmt.setInt(4, book.getBookTypeId());

int result = pstmt.executeUpdate();

dbUtil.close(pstmt, con);

return result;

}

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

Book book = new Book("java测试", 99, "测试", 1);

int result = addBook(book);

if(result ==1) {

System.out.println("添加成功");

}else {

System.out.println("添加失败");

}

}

}

  三、使用PreparedStatement接口实现更新数据操作

public class demo02 {

private static DbUtil dbUtil = new DbUtil();

private static int updateBook(Book book)throws Exception{

Connection con = dbUtil.getCon();

String sql = "update t_book set bookName=?,price=?,author=?,bookTypeId=? where id=?";

PreparedStatement pstmt = con.prepareStatement(sql);

pstmt.setString(1, book.getBookName());

pstmt.setFloat(2, book.getPrice());

pstmt.setString(3, book.getAuthor());

pstmt.setInt(4, book.getBookTypeId());

pstmt.setInt(5, book.getId());

int result = pstmt.executeUpdate();

dbUtil.close(pstmt, con);

return result;

}

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

Book book = new Book(1, "book1", 222, "book作者", 3);

int result = updateBook(book);

if(result ==1) {

System.out.println("更新数据成功");

}else {

System.out.println("更新数据失败");

}

}

}

  四、使用PreparedStatement接口实现删除数据操作

public class Demo3 {

private static DbUtil dbUtil = new DbUtil();

private static int deleteBook(int id) throws Exception{

Connection con = dbUtil.getCon();

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

PreparedStatement pstmt = con.prepareStatement(sql);

pstmt.setInt(1, id);

int result = pstmt.executeUpdate();

dbUtil.close(pstmt, con);

return result;

}

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

int result = deleteBook(6);

if(result ==1 ) {

System.out.println("删除成功");

}else {

System.out.println("删除失败");

}

}

}

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