如何在 JDBC 创建保存点？
一个保存点对象用于保存数据库的当前状态，之后可以回滚到该数据库的状态。保存点类似于 SQL 事务，如果当前事务中出现问题，通常会回滚。Java 中连接接口的连接.设置保存点()方法用于创建一个对象，该对象引用事务中数据库的当前状态。以下示例显示了保存点和回滚在 JDBC 应用程序中的用法。
语法
connection.setSavepoint()
返回:返回一个新的保存点对象。
异常:抛出 SQLException 如果发生数据库访问错误，在参与分布式事务时调用此方法，在关闭的连接上调用此方法，或者此 connection 对象当前处于自动提交模式。如果 JDBC 驱动程序不支持此方法，将引发 sqlffeaturenotsupportdexception。
例
Java 语言(一种计算机语言，尤用于创建网站)
// Java program to demonstrate how to make a save point
import java.io.*;
import java.sql.*;
class GFG {
public static void main(String[] args)
{
// db credentials
String jdbcEndpoint
= "jdbc:mysql://localhost:3000/GEEKSFORGEEKS";
String userid = "GFG";
String password = "GEEKSFORGEEKS";
// create a connection to db
Connection connection = DriverManager.getConnection(
jdbcEndpoint, userid, password);
// construct a query
Statement deleteStmt = connection.createStatement();
String deleteQuery
= "DELETE FROM USER WHERE AGE > 15";
// Disable auto commit to connection
connection.setAutoCommit(false);
/* Table USER
+--------+---------+------------+
| USR_ID | NAME | AGE |
+--------+---------+------------+
| 1 | GFG_1 | 10 |
| 2 | GFG_2 | 20 |
| 3 | GFG_3 | 25 |
+--------+---------+------------+
*/
// Create a savepoint object before executing the
// deleteQuery
Savepoint beforeDeleteSavepoint
= connection.setSavepoint();
// Executing the deleteQuery
ResultSet res
= deleteStmt.executeQuery(deleteQuery);
/* Table USER after executing deleteQuery
+--------+---------+------------+
| USR_ID | NAME | AGE |
+--------+---------+------------+
| 1 | GFG_1 | 10 |
+--------+---------+------------+
*/
// Rollback to our beforeDeleteSavepoint
connection.rollback(beforeDeleteSavepoint);
connection.commit();
/* Table USER after rollback
+--------+---------+------------+
| USR_ID | NAME | AGE |
+--------+---------+------------+
| 1 | GFG_1 | 10 |
| 2 | GFG_2 | 20 |
| 3 | GFG_3 | 25 |
+--------+---------+------------+
*/
}
}
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