8、9

1.删除、修改
2.查询

testJDBC/JDBCDemo1/src/com/msb/test1/TestJDBC4.java

@@ -0,0 +1,87 @@
+package com.msb.test1;
+
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.SQLException;
+import java.sql.Statement;
+
+public class TestJDBC4 {
+    public static String driver = "com.mysql.cj.jdbc.Driver";
+    public static String url = "jdbc:mysql://127.0.0.1:3306/mydb?useSSL=false&useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai";
+    public static String user = "root";
+    public static String password = "Fnst1234";
+
+
+    public static void main(String[] args) {
+//        testDelete();
+        testUpdate();
+    }
+
+    public static void testUpdate() {
+        Connection connection = null;
+        Statement statement = null;
+
+        try {
+            // 选择数据库
+//        Driver driver = new com.mysql.cj.jdbc.Driver();
+//        DriverManager.registerDriver(driver);
+            Class.forName(driver);
+
+            // 建立连接
+            connection = DriverManager.getConnection(url, user, password);
+
+            // 执行sql
+            statement = connection.createStatement();
+            String sql = "update dept set dname='总部',loc='北京' where deptno=51";
+            int rows = statement.executeUpdate(sql);
+            System.out.println("影响行数据:" + rows);
+        } catch (Exception e) {
+            e.printStackTrace();
+        } finally {
+            try {
+                if (statement != null) {
+                    statement.close();
+                }
+                if (connection != null) {
+                    connection.close();
+                }
+            } catch (SQLException e) {
+                e.printStackTrace();
+            }
+        }
+    }
+
+    public static void testDelete() {
+        Connection connection = null;
+        Statement statement = null;
+
+        try {
+            // 选择数据库
+//        Driver driver = new com.mysql.cj.jdbc.Driver();
+//        DriverManager.registerDriver(driver);
+            Class.forName(driver);
+
+            // 建立连接
+            connection = DriverManager.getConnection(url, user, password);
+
+            // 执行sql
+            statement = connection.createStatement();
+            String sql = "delete from dept where deptno=40;";
+            int rows = statement.executeUpdate(sql);
+            System.out.println("影响行数据:" + rows);
+        } catch (Exception e) {
+            e.printStackTrace();
+        } finally {
+            try {
+                if (statement != null) {
+                    statement.close();
+                }
+                if (connection != null) {
+                    connection.close();
+                }
+            } catch (SQLException e) {
+                e.printStackTrace();
+            }
+        }
+    }
+}

testJDBC/JDBCDemo1/src/com/msb/test1/TestJDBC5.java

@@ -0,0 +1,63 @@
+package com.msb.test1;
+
+import java.sql.*;
+
+public class TestJDBC5 {
+    public static String driver = "com.mysql.cj.jdbc.Driver";
+    public static String url = "jdbc:mysql://127.0.0.1:3306/mydb?useSSL=false&useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai";
+    public static String user = "root";
+    public static String password = "Fnst1234";
+
+
+    public static void main(String[] args) {
+        testQuery();
+    }
+
+    public static void testQuery() {
+        Connection connection = null;
+        Statement statement = null;
+        ResultSet resultSet = null;
+
+        try {
+            // 选择数据库
+//        Driver driver = new com.mysql.cj.jdbc.Driver();
+//        DriverManager.registerDriver(driver);
+            Class.forName(driver);
+
+            // 建立连接
+            connection = DriverManager.getConnection(url, user, password);
+
+            // 执行sql
+            statement = connection.createStatement();
+            String sql = "select * from emp;";
+            resultSet = statement.executeQuery(sql);
+            while (resultSet.next()) {
+                int empno = resultSet.getInt("empno");
+                String ename = resultSet.getString("ename");
+                String job = resultSet.getString("job");
+                int mgr = resultSet.getInt("mgr");
+                Date hiredate = resultSet.getDate("hiredate");
+                double sal = resultSet.getDouble("sal");
+                double comm = resultSet.getDouble("comm");
+                int deptno = resultSet.getInt("deptno");
+                System.out.println("" + empno + "\t" + ename + "\t" + job + "\t" + mgr + "\t" + hiredate + "\t" + sal + "\t" + comm + "\t" + deptno + "\t");
+            }
+        } catch (Exception e) {
+            e.printStackTrace();
+        } finally {
+            try {
+                if (resultSet != null) {
+                    resultSet.close();
+                }
+                if (statement != null) {
+                    statement.close();
+                }
+                if (connection != null) {
+                    connection.close();
+                }
+            } catch (SQLException e) {
+                e.printStackTrace();
+            }
+        }
+    }
+}