如何使用JDBC从数据库中获取特定行的当前值？
ResultSet接口的refreshRow()方法使用数据库中的最新值刷新当前行。
rs.refreshRow()
假设我们有一个名为cricketers_data的表，其中包含7条记录，如下所示：
+----+------------+------------+---------------+----------------+-------------+ | ID | First_Name | Last_Name | Year_Of_Birth | Place_Of_Birth | Country | +----+------------+------------+---------------+----------------+-------------+ | 1 | Shikhar | Dhawan | 1981-12-05 | Delhi | India | | 2 | Jonathan | Trott | 1981-04-22 | CapeTown | SouthAfrica | | 3 | Lumara | Sangakkara | 1977-10-27 | Matale | Srilanka | | 4 | Virat | Kohli | 1988-11-05 | Mumbai | India | | 5 | Rohit | Sharma | 1987-04-30 | Nagpur | India | | 6 | Ravindra | Jadeja | 1988-12-06 | Nagpur | India | | 7 | James | Anderson | 1982-06-30 | Burnely | England | +----+------------+------------+---------------+----------------+-------------+
随后的JDBC程序更新表的内容并使用refreshRow()方法检索新值。
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
public class ResultSet_CurrentValue {
public static void main(String args[])throws Exception {
//注册驱动程序
DriverManager.registerDriver(new com.mysql.jdbc.Driver());
//获得连接
String mysqlUrl = "jdbc:mysql://localhost/mydatabase";
Connection con = DriverManager.getConnection(mysqlUrl, "root", "password");
System.out.println("Connection established......");
con.setAutoCommit(false);
//创建一个Statement对象
Statement stmt = con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_UPDATABLE);
//查询以获取employee_data表的内容
String query = "select * from Cricketers_Data";
//执行查询
ResultSet rs = stmt.executeQuery(query);
rs.absolute(4);
System.out.print("id: "+rs.getInt(1)+", ");
System.out.print("First name: "+rs.getString(2)+", ");
System.out.print("Last name: "+rs.getString(3)+", ");
System.out.print("Year of birth: "+rs.getDate(4)+", ");
System.out.print("Place of birth: "+rs.getString(5)+", ");
System.out.print("Country: "+rs.getString(6));
System.out.println(" ");
rs.absolute(4);
rs.updateString("Place_Of_Birth", "Delhi");
rs.refreshRow();
rs.absolute(4);
System.out.print("id: "+rs.getInt(1)+", ");
System.out.print("First name: "+rs.getString(2)+", ");
System.out.print("Last name: "+rs.getString(3)+", ");
System.out.print("Year of birth: "+rs.getDate(4)+", ");
System.out.print("Place of birth: "+rs.getString(5)+", ");
System.out.print("Country: "+rs.getString(6));
System.out.println(" ");
con.commit();
rs.close();
stmt.close();
}
}输出结果
Connection established...... id: 4, First name: Virat, Last name: Kohli, Year of birth: 1988-11-05, Place of birth: Mumbai, Country: India id: 4, First name: Virat, Last name: Kohli, Year of birth: 1988-11-05, Place of birth: Delhi, Country: India