diff --git "a/49 \346\235\216\350\210\222\346\261\266/20230523 Tomcat.md" "b/49 \346\235\216\350\210\222\346\261\266/20230523 Tomcat.md"
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index 0000000000000000000000000000000000000000..04b5bcafc518c920f3ea3f1f61dfca7dd6cf7887
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@@ -0,0 +1,117 @@
+查询
+
+```java
+public class Select {
+    private static String url="jdbc:mysql:///student_db?useSSL=false&characterEncoding=utf8";
+    private static String user="root";
+    private static String password="123456";
+    static {
+        try {
+            Class.forName("com.mysql.jdbc.Driver");
+        } catch (ClassNotFoundException e) {
+            e.printStackTrace();
+            System.out.println("驱动包加载异常");
+        }
+    }
+    public static Connection getconn(){
+        Connection conn = null;
+        try {
+            conn = DriverManager.getConnection(url, user, password);
+        } catch (SQLException e) {
+            e.printStackTrace();
+        }
+        return conn;
+    }
+    public static ResultSet query(String sql, String ...Val){
+        ResultSet rst = null;
+        try {
+            Connection ge = getconn();
+            PreparedStatement prt = ge.prepareStatement(sql);
+            for (int i = 0; i < Val.length; i++) {
+                prt.setString((i+1),Val[i]);
+            }
+            rst = prt.executeQuery();
+        } catch (SQLException e) {
+            e.printStackTrace();
+        }
+        return rs;
+    }
+}
+```
+
+测试类
+
+```java
+@WebServlet("/stu")
+public class SelectTest extends HttpServlet {
+    @Override
+    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
+        resp.setContentType("text/html;charset=utf-8");
+        resp.setCharacterEncoding("utf-8");
+        PrintWriter wr = resp.getWriter();
+        String sql="select * from studen";
+        ResultSet que =Select.query(sql);
+        wr.write("<table border=1>");
+        wr.write("<tr><th>编号</th><th>姓名</th><th>性别</th></tr>");
+        try {
+            while (que.next()){
+                String id=que.getString(1);
+                String name=que.getString(2);
+                String sex= que.getString(3);
+                wr.write("<tr><td>"+id+"</td><td>"+name+"</td><td>"+sex+"</td></tr>");
+            }
+        } catch (SQLException e) {
+            throw new RuntimeException(e);
+        }
+        wr.write("</table>");
+    }
+
+    @Override
+    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
+        super.doPost(req, resp);
+    }
+}
+```
+
+增删改
+
+```java
+public class ZSG {
+    private static String url="jdbc:mysql:///student_db?useSSL=false&characterEncoding=utf8";
+    private static String user="root";
+    private static String password="123456";
+    static {
+        try {
+            Class.forName("com.mysql.jdbc.Driver");
+        } catch (ClassNotFoundException e) {
+            e.printStackTrace();
+            System.out.println("驱动包加载异常");
+        }
+    }
+    public static Connection getconn(){
+        Connection conn = null;
+        try {
+            conn = DriverManager.getConnection(url, user, password);
+        } catch (SQLException e) {
+            e.printStackTrace();
+        }
+        return conn;
+    }
+    public static int query(String sql, String ...Val) {
+        int ii = 0;
+        try {
+            Connection ge = getconn();
+            PreparedStatement prt = ge.prepareStatement(sql);
+            for (int i = 0; i < Val.length; i++) {
+                prt.setString((i + 1), Val[i]);
+            }
+            ii = prt.executeUpdate();
+        } catch (SQLException e) {
+            e.printStackTrace();
+        }
+        return ii;
+    }
+}
+```
+
+