JDBC学习笔记(5)：数据库的基本操作CRUD

1.查询

public static void read() throws SQLException {
        Connection conn = null;
        Statement stmt = null;
        ResultSet rs = null;

        try {
            conn = JdbcUtils.getConnection();
            stmt = conn.createStatement();
            rs = stmt.executeQuery("select * from user");

            while(rs.next()) {
                System.out.println(rs.getInt("id") + "\t"
                        + rs.getString("name") + "\t"
                        + rs.getDate("birthday") + "\t"
                        + rs.getFloat("money"));
            }
        } finally {
            JdbcUtils.close(rs, stmt, conn);
        }
    }

【运行结果】：

1    zhangs    1985-01-01    100.0

2    lisi    1986-01-01    200.0

3    wangwu    1987-01-01    300.0

2.增减一条记录，由于id是自增的，所以不需要重复插入数据：

public static void create() throws SQLException {
        Connection conn = null;
        Statement stmt = null;
        ResultSet rs = null;

        try {
            conn = JdbcUtils.getConnection();
            stmt = conn.createStatement();
            String sql = "insert into user(name,birthday,money) values(‘zhaoliu‘,‘1990-01-01‘,400)";
            int i = stmt.executeUpdate(sql);
            System.out.println("i="+i);
        } finally {
            JdbcUtils.close(rs, stmt, conn);
        }
    }

【运行结果】：

i=1  //表示成功插入一条记录

【查询数据库结果】：多了一条记录

3.将id=1的money修改为400

public static void update() throws SQLException {
        Connection conn = null;
        Statement stmt = null;
        ResultSet rs = null;

        try {
            conn = JdbcUtils.getConnection();
            stmt = conn.createStatement();

            String sql = "update user set money=400 where id=1";
            int i = stmt.executeUpdate(sql);
            System.out.println("i = " + i);
        } finally {
            JdbcUtils.close(rs, stmt, conn);
        }

    }

【运行结果】：

i = 1

【查询数据库结果】：

4.删除id=4的记录

public static void delete() throws SQLException {
        Connection conn = null;
        Statement stmt = null;
        ResultSet rs = null;

        try {
            conn = JdbcUtils.getConnection();
            stmt = conn.createStatement();
            String sql = "delete from user where id=4";
            int i = stmt.executeUpdate(sql);
            System.out.println("i=====" + i);
        } finally{
            JdbcUtils.close(rs, stmt, conn);
        }
    }

【运行结果】：

i=====1

【查询数据库结果】：