JDBC简单使用

1. 首先导包，放在src -> lib下

打开项目结构，添加导入的包为库

基础语法

Statement statement = conn.createStatement();
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1.execute(String query)方法用来执行任意的SQL语句查询，如果查询的结果是一个ResultSet,这个方法就返回true,
    如果结果不是ResultSet，比如：insert或update，就会返回false.可以通过getResultSet方法来获取ResultSet。
2.executeQuery(String query)接口用来执行select查询，并返回ResultSet,
    即便查询不到记录，返回的ResultSet也不会为null.
3.executeUpdate(String query)方法用来执行insert，delete或者update语句，返回值是int类型，
    如果是DML语句，则是更新的条数，如果是DDL，则返回0

普通使用

private String connStr = "jdbc:mysql://localhost:3306/red1";
private String user = "root";
private String pwd = "123456";

//依赖
Class.forName("com.mysql.cj.jdbc.Driver");

//获得连接
Connection conn = DriverManager.getConnection(connStr, user, pwd);
Statement statement = conn.createStatement();
//sql语句
String sql="select * from table";

//执行查询操作
statement.execute(sql);


//关闭数据库连接
statement.close();
conn.close();

新增

    public void addKeShi(String str1, String str2) throws ClassNotFoundException, SQLException {
        //获得连接
        Connection conn = DriverManager.getConnection(connStr, user, pwd);
        Statement statement = conn.createStatement();
        //sql
        String sql = "INSERT INTO ke_shi(name,describe1) VALUES ('" + str1 + "','" + str2 + "')";
//        System.out.println(sql);
        int num = statement.executeUpdate(sql);
        if (num == 1) {
            System.out.println("科室新增成功\n");
        } else {
            System.out.println("科室新增失败，SQL语句为：" + sql + "\n");
        }
        //关闭数据库连接
        statement.close();
        conn.close();
    }

查询所有

    public List<KeShi> getAllKeShi() throws ClassNotFoundException, SQLException {
        //获得连接
        Connection conn = DriverManager.getConnection(connStr, user, pwd);
        Statement statement = conn.createStatement();
        //sql
        String sql = "SELECT * FROM ke_shi";
        ResultSet rs = statement.executeQuery(sql);
        List<KeShi> list = new ArrayList<>();
        KeShi keShi=null;
        while (rs.next()) {
            //获取当前记录中的数据
            //方法1. 通过字段索引获取id，列索引是从1开始的。
            int id = rs.getInt(1);
            String name = rs.getString(2);
            String describe = rs.getString(3);
            keShi=new KeShi(id,name,describe);
            list.add(keShi);
        }
        //关闭数据库连接
        statement.close();
        conn.close();
        return list;
    }

修改

    public void changeKeShiByID(int id, String str1, String str2) throws ClassNotFoundException, SQLException {
        //获得连接
        Connection conn = DriverManager.getConnection(connStr, user, pwd);
        Statement statement = conn.createStatement();
        //sql
        String sql = "UPDATE ke_shi SET  name='" + str1 + "',describe1='" + str2 + "' WHERE id = " + id;
//        System.out.println(sql);
        int num = statement.executeUpdate(sql);
        if (num == 1) {
            System.out.println("科室修改成功\n");
        } else {
            System.out.println("科室修改失败，SQL语句为：" + sql + "\n");
        }
        //关闭数据库连接
        statement.close();
        conn.close();
    }

删除

    public void deleteKeShiByID(int id) throws ClassNotFoundException, SQLException {
        //获得连接
        Connection conn = DriverManager.getConnection(connStr, user, pwd);
        Statement statement = conn.createStatement();
        //sql
        String sql = "DELETE FROM  ke_shi WHERE id =" + id;
//        System.out.println(sql);
        int num = statement.executeUpdate(sql);
        if (num == 1) {
            System.out.println("科室删除成功\n");
        } else {
            System.out.println("科室删除失败，SQL语句为：" + sql + "\n");
        }
        //关闭数据库连接
        statement.close();
        conn.close();
    }