JDBC之——Statement实现对数据库的增删改操作

一、Statement接口引入

作用：用于执行静态SQL语句并返回它所生成结果的对象

int executeUpdate(String sql)  执行给定SQL语句，该语句可能为INSERT、UPDATE、或DELETE语句，或者不返回任何内容的SQL语句（如SQLDDL语句）。

void close()  立即释放此Statement对象的数据库和JDBC资源，而不是等待该对象自动关闭时发生此操作。

二、使用Statement接口实现添加数据操作

demo1:

public class Demo1 {
	public static void main(String[] args) throws Exception {
		DbUtil dbUtil = new DbUtil();
		String sql = "insert into t_book values(null,'java牛逼',888,'B哥',1)";
		Connection con = dbUtil.getCon();//获取数据库连接
		Statement stmt = con.createStatement();//获取Statement
		int result = stmt.executeUpdate(sql);
		System.out.println("操作的结果："+result+"数据");
		stmt.close();//关闭statement
		con.close();//关闭连接
	}
}

demo2:

//工具类
public class DbUtil {
	//数据库地址
	private static String dbUrl="jdbc:mysql://localhost:3306/db_book";
	//用户名
	private static String dbUserName="root";
	//密码
	private static String dbPassword="root";
	//驱动名称
	private static String jdbcName="com.mysql.jdbc.Driver";
	/**
	 * 获取数据库连接
	 * 	1.加载数据库驱动
	 *  2.获取数据库连接
	 */
	public Connection getCon() throws Exception {
		Class.forName(jdbcName);//加载数据库驱动
		Connection con = DriverManager.getConnection(dbUrl, dbUserName, dbPassword);
		return con;
	}
	/**
	 * 关闭连接
	 */
	public void close(Statement stmt,Connection con) throws Exception {
		if(stmt!=null) {
			stmt.close();
		}
		if(con!=null) {
			con.close();
		}
	}
}

//Demo2
public class Demo2 {
	private static DbUtil dbUtil = new DbUtil();
	/**
	 * 添加图书
	 */
	private static int addBook(String bookName,float price,String author,int bookTypeId) throws Exception {
		Connection con = dbUtil.getCon();
		String sql = "insert into t_book values(null,'"+bookName+"',"+price+",'"+author+"',"+bookTypeId+")";
		Statement stmt = con.createStatement();//创建Statement
		int result = stmt.executeUpdate(sql);
		dbUtil.close(stmt, con);//关闭Statement和连接
		return result;
	}
	public static void main(String[] args) throws Exception {
		String bookName = "Java你牛";
		float price = 100;
		String author = "牛牛";
		int bookTypeId = 1;
		int result = addBook(bookName, price, author, bookTypeId);
		if(result == 1) {
			System.out.println("添加成功！");
		}else {
			System.out.println("添加失败！");
		}
	}
}

demo3:以对象的方式

//工具类
public class DbUtil {
	
	//数据库地址
	private static String dbUrl="jdbc:mysql://localhost:3306/db_book";
	//用户名
	private static String dbUserName="root";
	//密码
	private static String dbPassword="root";
	//驱动名称
	private static String jdbcName="com.mysql.jdbc.Driver";
	
	/**
	 * 获取数据库连接
	 * 	1.加载数据库驱动
	 *  2.获取数据库连接
	 */
	public Connection getCon() throws Exception {
		
		Class.forName(jdbcName);//加载数据库驱动
		
		Connection con = DriverManager.getConnection(dbUrl, dbUserName, dbPassword);
		
		return con;
	}
	
	/**
	 * 关闭连接
	 */
	public void close(Statement stmt,Connection con) throws Exception {
		if(stmt!=null) {
			stmt.close();
		}
		if(con!=null) {
			con.close();
		}
	}
}


//book对象
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;
	}
        。。。//get和set方法省略
}

//demo3
public class Demo3 {
	private static DbUtil dbUtil = new DbUtil();
	
	/**
	 * 添加图书2  以对象的方式
	 */
	private static int addBook2(Book book) throws Exception{
		Connection con = dbUtil.getCon();
		String sql = "insert into t_book values(null,'"+book.getBookName()+"',"+book.getPrice()+",'"+book.getAuthor()+"',"+book.getBookTypeId()+")";
		Statement stmt = con.createStatement();//创建Statement
		int result = stmt.executeUpdate(sql);
		dbUtil.close(stmt, con);//关闭Statement和连接
		return result;
	}
	public static void main(String[] args) throws Exception {
		Book book = new Book("Java牛牛2", 99, "牛牛2", 2);
		int result = addBook2(book);
		
	}
}

 

三、使用Statement接口实现更新数据操作

//工具类
public class DbUtil {
	//数据库地址
	private static String dbUrl="jdbc:mysql://localhost:3306/db_book";
	//用户名
	private static String dbUserName="root";
	//密码
	private static String dbPassword="root";
	//驱动名称
	private static String jdbcName="com.mysql.jdbc.Driver";
	/**
	 * 获取数据库连接
	 * 	1.加载数据库驱动
	 *  2.获取数据库连接
	 */
	public Connection getCon() throws Exception {
		
		Class.forName(jdbcName);//加载数据库驱动
		
		Connection con = DriverManager.getConnection(dbUrl, dbUserName, dbPassword);
		
		return con;
	}
	/**
	 * 关闭连接
	 */
	public void close(Statement stmt,Connection con) throws Exception {
		if(stmt!=null) {
			stmt.close();
		}
		if(con!=null) {
			con.close();
		}
	}
}


//book对象
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;
	}
}

//demo测试类
public class Demo1 {
	private static DbUtil dbUtil = new DbUtil();
	private static int updateBook(Book book) throws Exception {
		Connection conn = dbUtil.getCon();//获取连接
		String sql = "update t_book set bookName='"+book.getBookName()
				+"',price="+book.getPrice()+",author='"+book.getAuthor()
				+"',bookTypeId="+book.getBookTypeId()+" where id="
				+book.getId();
		Statement stmt = conn.createStatement();
		int result = stmt.executeUpdate(sql);
		dbUtil.close(stmt, conn);//关闭statemet和连接
		return result;
	}
	public static void main(String[] args) throws Exception {
		Book book = new Book(3, "java牛牛222", 123, "牛哥", 1);
		int result = updateBook(book);
		System.out.println("更新了"+result+"数据");
		if(result==1) {
			System.out.println("更新成功");
		}else {
			System.out.println("更新失败");
		}
	}
}

四、使用Statement接口实现删除数据操作

public class Demo2 {
	private static DbUtil dbUtil = new DbUtil();
	private static int deleteBook(int id) throws Exception{
		Connection con = dbUtil.getCon();//获取连接
		String sql = "delete from t_book where id = "+id;
		Statement stmt = con.createStatement();//创建Statement
		int result = stmt.executeUpdate(sql);
		dbUtil.close(stmt, con);
		return result;
	}
	public static void main(String[] args) throws Exception {
		int result = deleteBook(3);
		if(result ==1) {
			System.out.println("删除成功！");
		}else {
			System.out.println("删除失败！");
		}
	}
}