diff --git "a/17\351\203\221\347\216\256\351\224\213/20230517 JDBC.md" "b/17\351\203\221\347\216\256\351\224\213/20230517 JDBC.md" new file mode 100644 index 0000000000000000000000000000000000000000..f4a2b13f2ffb44dee738f16d7cf003d9a26a2c06 --- /dev/null +++ "b/17\351\203\221\347\216\256\351\224\213/20230517 JDBC.md" @@ -0,0 +1,169 @@ +### JDBC作业： + +1. MySQL中创建一个数据库student_db + +2. 库中创建student表 + +3. 表中数据如下 + +4. | 编号 | 姓名 | 性别 | + | ---- | ---- | ---- | + | 1 | 张三 | 男 | + | 2 | 李四 | 女 | + | 3 | 王五 | 男 | + + ~~~MySQL + create database student_db default char set utf8; + use student_db; + create table student_db ( + id int , + name varchar(10), + sex char + ); + insert into student_db values + (1,'张三','男'), + (2,'李四','女'), + (3,'王五','男'); + ~~~ + + + +5. 编写java 4个类，分别实现以下功能 + + 1. 查询功能，查询student中所有数据 + 2. 添加功能 + 3. 修改功能 + 4. 删除功能 + +6. 扩展题【预习题】 + + 1. 能否实现一个类中，用四个方法来实现上面4个类的功能 + 2. 能否实现将查询的结果，封装成java对象 + + ~~~java + import java.sql.*; + + public class Jdbc { + public static void main(String[] args) { + try { + select();//查询 + update();//修改 + insert();//添加 + delete();//删除 + } catch (SQLException e) { + throw new RuntimeException(e); + } catch (ClassNotFoundException e) { + throw new RuntimeException(e); + } + + } + public static void select() throws SQLException, ClassNotFoundException { + //1.注册驱动 + Class.forName("com.mysql.jdbc.Driver"); + //2.获取连接对象 + String url = "jdbc:mysql://localhost:3306/student_db?useSSL=false&useUnicode=true&characterEncoding=utf8"; + String username = "root"; + String password = "root"; + Connection conn = DriverManager.getConnection(url,username,password); + //3.定义SQL + String sql = "select * from sonyang;"; + + //4.获取执行SQL + Statement st = conn.createStatement(); + + //5.执行SQL + ResultSet rs = st.executeQuery(sql); + //6.处理返回结果 + System.out.println("id "+"name"); + while (rs.next()){ + int id = rs.getInt("id"); + String name = rs.getString("name"); + System.out.println(id+" "+name); + } + //7.释放资源 + rs.close(); + st.close(); + conn.close(); + } + public static void update() throws SQLException, ClassNotFoundException { + //1.注册驱动 + Class.forName("com.mysql.jdbc.Driver"); + //2.获取连接对象 + String url = "jdbc:mysql://localhost:3306/student_db?useSSL=false&useUnicode=true&characterEncoding=utf8"; + String username = "root"; + String password = "root"; + Connection conn = DriverManager.getConnection(url,username,password); + //3.定义SQL + String sql = "update sonyang set name = '宋扬2号'where id=1"; + + //4.获取执行SQL + Statement st = conn.createStatement(); + + //5.执行SQL + int i = st.executeUpdate(sql); + //6.处理返回结果 + if (i>0){ + System.out.println("修改成功"); + }else { + System.out.println("修改失败"); + } + //7.释放资源 + st.close(); + conn.close(); + } + public static void insert() throws ClassNotFoundException, SQLException { + //1.注册驱动 + Class.forName("com.mysql.jdbc.Driver"); + //2.获取连接对象 + String url = "jdbc:mysql://localhost:3306/student_db?useSSL=false&useUnicode=true&characterEncoding=utf8"; + String username = "root"; + String password = "root"; + Connection conn = DriverManager.getConnection(url,username,password); + //3.定义SQL + String sql = "insert into sonyang values (2,'邓琪plus')"; + //4.获取执行SQL + Statement st = conn.createStatement(); + + //5.执行SQL + int i = st.executeUpdate(sql); + //6.处理返回结果 + if (i>0){ + System.out.println("添加"+i+"行数据成功"); + }else { + System.out.println("添加失败"); + } + //7.释放资源 + st.close(); + conn.close(); + } + public static void delete() throws ClassNotFoundException, SQLException { + //1.注册驱动 + Class.forName("com.mysql.jdbc.Driver"); + //2.获取连接对象 + String url = "jdbc:mysql://localhost:3306/student_db?useSSL=false&useUnicode=true&characterEncoding=utf8"; + String username = "root"; + String password = "root"; + Connection conn = DriverManager.getConnection(url,username,password); + //3.定义SQL + String sql = "delete from sonyang where name='张三'"; + //4.获取执行SQL + Statement st = conn.createStatement(); + //5.执行SQL + int i = st.executeUpdate(sql); + //6.处理返回结果 + if (i>0){ + System.out.println("删除了"+i+"行数据成功"); + }else { + System.out.println("删除失败"); + } + //7.释放资源 + st.close(); + conn.close(); + + } + } + + ~~~ + + + diff --git "a/17\351\203\221\347\216\256\351\224\213/20230520\344\275\234\344\270\232.md" "b/17\351\203\221\347\216\256\351\224\213/20230520\344\275\234\344\270\232.md" new file mode 100644 index 0000000000000000000000000000000000000000..221fdc3e861042b40ad572997cf0053d71bd20d8 --- /dev/null +++ "b/17\351\203\221\347\216\256\351\224\213/20230520\344\275\234\344\270\232.md" @@ -0,0 +1,138 @@ +今天作业：使用新的执行SQL的对象，封装一个工具类，然后用这个工具类查询上次作业的数据库，实现将查询结果封装成学生对象，最后存入一个集合窗口，遍历之个集合的对象 + +```java +public class Studentdx { + private int id; + private String name; + private String sex; + + public Studentdx() { + } + + public Studentdx(int id, String name, String sex) { + this.id = id; + this.name = name; + this.sex = sex; + } + + public int getId() { + return id; + } + + public void setId(int id) { + this.id = id; + } + + public String getName() { + return name; + } + + public void setName(String name) { + this.name = name; + } + + public String getSex() { + return sex; + } + + public void setSex(String sex) { + this.sex = sex; + } +} +``` + +```java +import java.sql.*; +import java.util.ArrayList; + +public class Student { + private static final String url="jdbc:mysql://localhost:3306/student_db?useSSL=false&useUnicode=true&characterEncoding=utf8"; + private static final String user="root"; + private static final String pass ="200311"; + + static { + try { + Class.forName("com.mysql.cj.jdbc.Driver"); + + } catch (ClassNotFoundException e) { + throw new RuntimeException(e); + } + + } + + public static Connection link() throws SQLException { + Connection conn = DriverManager.getConnection(url, user, pass); + return conn; + } + //查询 + ArrayList list = new ArrayList<>(); + public static ArrayList Query(String sql,ArrayList list,String ...flop) throws SQLException { + Connection conn = link(); + PreparedStatement ps = conn.prepareStatement(sql); + for (int i = 0; i < flop.length; i++) { + ps.setString((i+1),flop[i]); + } + ResultSet rs = ps.executeQuery(); + while (rs.next()){ + Studentdx stu = new Studentdx(); + stu.setId(rs.getInt("id")); + stu.setName(rs.getString("name")); + stu.setSex(rs.getString("sex")); + list.add(stu); + } + return list; + } + //添加,删除,修改 + public static int update(String sql,String ...flop) throws SQLException { + Connection conn = link(); + PreparedStatement ps = conn.prepareStatement(sql); + for (int i = 0; i < flop.length; i++) { + ps.setString((i+1),flop[i]); + } + int i = ps.executeUpdate(); + return i; + } + //释放 + public static void release(Connection conn,PreparedStatement ps,ResultSet rs) throws SQLException { + if (rs!=null){ + rs.close(); + } + if (ps!=null){ + ps.close(); + } + if (conn!=null){ + conn.close(); + } + } + public static void release(Connection conn,PreparedStatement ps) throws SQLException { + if (ps!=null){ + ps.close(); + } + if (conn!=null){ + conn.close(); + } + } +} +``` + +```java +import java.sql.SQLException; +import java.util.ArrayList; + +public class Text2 { + public static void main(String[] args) throws SQLException { + //今天作业：使用新的执行SQL的对象，封装一个工具类， + // 然后用这个工具类查询上次作业的数据库，实现将查询结果封装成学生对象， + // 最后存入一个集合窗口，遍历之个集合的对象 + ArrayList list = new ArrayList<>(); + String sql = "select * from student"; + ArrayList liste = Student.Query(sql, list); + System.out.println("id\t姓名\t性别"); + for (int i = 0; i < liste.size(); i++) { + Studentdx stu = liste.get(i); + System.out.println(stu.getId()+"\t"+stu.getName()+"\t"+stu.getSex()); + } + } +} +``` +