先决条件：JDBC、SQL 视图。
视图就是任何已给定名称并保存在数据库中的 SELECT 查询。因此，视图有时称为命名查询或存储查询。
物化视图是与普通视图类似的视图，除了它们刷新更快的一个属性。当主表中发生任何更新时，这些视图会自动更新。
假设如果在主表中发生任何插入，则物化视图也会更新。在下面的程序中，我们试图展示物化视图是如何工作的。每个数据库软件的实际实现可能有所不同。
// Java Program to implementat
// Materialized view
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.Scanner;
import java.sql.PreparedStatement;
public class Materialised_View {
public static void main(String[] args)
{
// Declare connection and resultset objects
Connection conn;
ResultSet rs;
// Declare statement objects
Statement stmt, stmt1;
// query to retrieve the details of student table
String query = "select * from student;";
Scanner sc = new Scanner(System.in);
System.out.println("Student Table is Created as Follows:\n");
System.out.println
("*******Student*********\nsid\tsname\taddress\n---- ");
try {
// Register the mysql driver
DriverManager.registerDriver(new com.mysql.jdbc.Driver());
// get the connection
conn = DriverManager.getConnection
("jdbc:mysql:// localhost:3306/adbms_practicals", "root", "kernel");
// Initialize the statement object
stmt = conn.createStatement();
// execute the query and store the result
rs = stmt.executeQuery("select * from student;");
while (rs.next()) {
// Iterate through the result set and display
// content of each row of student table.
System.out.println(rs.getString(1) + "\t"
+ rs.getString(2) + "\t" + rs.getString(3));
}
System.out.println("\n\nView of this Student Table is As Follows:");
rs = stmt.executeQuery("select * from Student_Data2;");
System.out.println
("\n***********Student View*******\nsid\tsname\taddress\n-------");
while (rs.next()) {
// Iterate through the result set and display
// content of view of student table.
System.out.println(rs.getString(1) + "\t"
+ rs.getString(2) + "\t" + rs.getString(3));
}
while (true) {
// Perform the operations on table
System.out.println("Menu:\n1.Insert\n2.Delete\n3.
See Changes in View Student_Data2\n4.Exit\nEnter Choice:");
// take the input from user to insert / delete / see changes
int ch = sc.nextInt();
int sid;
String sname = "";
String address = "";
switch (ch) {
case 1:
System.out.println("Enter sid:");
sid = sc.nextInt();
System.out.println("Enter sname:");
sname = sc.nextLine();
System.out.println("Enter address:");
address = sc.nextLine();
// create the preparedStatement object and set the values
PreparedStatement st3 = conn.prepareStatement
("insert into student values(?, ?, ?);");
st3.setInt(1, sid);
st3.setString(2, sname);
st3.setString(3, address);
st3.executeUpdate();
// create the preparedStatement object and set the values
PreparedStatement st1 = conn.prepareStatement
("insert into Student_Data2 values(?, ?, ?);");
st1.setInt(1, sid);
st1.setString(2, sname);
st1.setString(3, address);
st1.executeUpdate(); // execute the preparedStatement to insert row
System.out.println("row inserted");
break;
case 2:
System.out.println("Enter sid to be deleted:");
sid = sc.nextInt();
// create the preparedStatement object and set the values
PreparedStatement st4 = conn.prepareStatement
("delete from Student_Data2 where sid=?;");
st4.setInt(1, sid);
PreparedStatement st2 = conn.prepareStatement
("delete from student where sid=?");
st2.setInt(1, sid);
// execute the preparedStatement to delete row
st2.executeUpdate();
System.out.println("row deleted");
break;
case 3:
System.out.println("\n\nChanges Done in the
Student table also Affects the View Student_Data2");
rs = stmt.executeQuery("select * from Student_Data2;");
System.out.println
("\n*****Student*******\nsid\tsname\taddress\n--------");
while (rs.next()) {
// Iterate through the result set and display
// recent changes of the table
// which got reflected in view.
System.out.println(rs.getString(1) + "\t"
+ rs.getString(2) + "\t" + rs.getString(3));
}
break;
case 4:
System.exit(0); // User wants to exit
break;
}
}
}
catch (Exception e) { // catch all exceptions here.
System.out.println(e);
}
}
}
输出：
Student Table is Created as Follows:
***********Student**************
sid sname address
-----------------------------------------------
131 Rohit Pawar Mumbai
141 Ashish Mane Pune
152 Sagar Gore Mumbai
155 Nitesh Chaure Nagpur
501 Ritesh Dev Chennai
531 Dev Khire Delhi
View of this Student Table is As Follows:
***********Student**************
sid sname address
-----------------------------------------------
131 Rohit Pawar Mumbai
141 Ashish Mane Pune
152 Sagar Gore Mumbai
155 Nitesh Chaure Nagpur
501 Ritesh Dev Chennai
531 Dev Khire Delhi
Menu:
1.Insert
2.Delete
3.See Changes in View Student_Data2
4.Exit
Enter Choice:1
Enter sid: 123
Enter sname: Amit Kumar
Enter address: Nanded
row inserted
Menu:
1.Insert
2.Delete
3.See Changes in View Student_Data2
4.Exit
Enter Choice:3
Changes Done in the Student table also Affects the View Student_Data2
***********Student**************
sid sname address
-----------------------------------------------
131 Rohit Pawar Mumbai
141 Ashish Mane Pune
152 Sagar Gore Mumbai
155 Nitesh Chaure Nagpur
501 Ritesh Dev Chennai
531 Dev Khire Delhi
123 Amit Kumar Nanded
Menu:
1.Insert
2.Delete
3.See Changes in View Student_Data2
4.Exit
Enter Choice:2
Enter sid to be deleted: 123
row deleted
Menu:
1.Insert
2.Delete
3.See Changes in View Student_Data2
4.Exit
Enter Choice:3
Changes Done in the Student table also Affects the View Student_Data2
***********Student**************
sid sname address
-----------------------------------------------
131 Rohit Pawar Mumbai
141 Ashish Mane Pune
152 Sagar Gore Mumbai
155 Nitesh Chaure Nagpur
501 Ritesh Dev Chennai
531 Dev Khire Delhi
Menu:
1.Insert
2.Delete
3.See Changes in View Student_Data2
4.Exit
Enter Choice:4
解释 ：
学生表和学生视图在输出开始时打印。然后，如果用户选择选项 1 将数据插入学生表 ‘123 Amit Kumar Nanded’ 中，则此新行将插入表中。然后用户选择第三个选项来查看学生视图中是否反映了更改，选择第三个选项后，我们可以看到学生视图中也添加了相同的条目。然后用户选择第二个选项并提供 sid = 123 作为输入以从学生表中删除条目 同样，我们可以看到相同的条目也从学生视图中删除。这就是刷新物化视图的工作原理。
请注意，每个数据库软件的内部实现可能不同。