如何使用JDBC API从Oracle数据库中的现有表中检索记录？
您可以使用UPDATE查询来更新/修改表中记录的现有内容。使用此功能，您可以更新表的所有记录或特定记录。
语法
UPDATE table_name SET column1 = value1, column2 = value2...., columnN = valueN WHERE [condition];
要使用JDBCAPI更新表中记录的内容，您需要-
注册驱动程序：使用DriverManager 类的registerDriver()方法注册驱动程序类。将驱动程序类名称作为参数传递给它。
建立连接：使用DriverManager 类的getConnection() 方法连接到数据库。将URL（字符串），用户名（字符串），密码（字符串）作为参数传递给它。
创建语句：使用Connection 接口的 createStatement()方法创建一个Statement对象。
执行查询：使用executeUpdate()Statement接口的方法执行查询。
让我们使用CREATE语句在Oracle数据库中创建一个带有名称调度 的表，如下所示-
CREATE TABLE Dispatches( PRODUCTNAME VARCHAR2(20), CUSTOMERNAME VARCHAR2(20), DISPATCHDATE DATE, DELIVERYTIME TIMESTAMP(6), PRICE NUMBER(38), LOCATION VARCHAR2(20) );
现在，我们将使用INSERT语句在分派 表中插入5条记录-
insert into dispatches values('Key-Board', 'Raja', TO_DATE('2019-09-01', 'yyyy/mm/dd'), TO_DATE('11:00:00', 'hh:mi:ss'), 7000, 'India');
insert into dispatches values('Earphones', 'Roja', TO_DATE('2019-05-01', 'yyyy/mm/dd'), TO_DATE('11:00:00', 'hh:mi:ss'), 2000, 'Vishakhapatnam');
insert into dispatches values('Mouse', 'Puja', TO_DATE('2019-03-01', 'yyyy/mm/dd'), TO_DATE('10:59:59', 'hh:mi:ss'), 3000, 'Vijayawada');
insert into dispatches values('Mobile', 'Vanaja', TO_DATE('2019-03-01', 'yyyy/mm/dd'), TO_DATE('10:10:52', 'hh:mi:ss'), 9000, 'Chennai');
insert into dispatches values('Headset', 'Jalaja', TO_DATE('2019-04-06', 'yyyy/mm/dd'), TO_DATE('11:08:59', 'hh:mi:ss' ), 6000, 'Goa');接下来的JDBC程序建立与Oracle数据库的连接，并将每个产品的价格提高3000。
示例
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class UpdateRecordsExample {
public static void main(String args[]) throws SQLException {
//注册驱动程序
DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());
//获得连接
String oracleUrl = "jdbc:oracle:thin:@localhost:1521/xe";
Connection con = DriverManager.getConnection(oracleUrl, "system", "password");
System.out.println("Connection established......");
//创建语句
Statement stmt = con.createStatement();
//查询更新记录，将所有项目的价格提高3000-
String query = "Update dispatches set PRICE = PRICE+3000";
//执行查询
int i = stmt.executeUpdate(query);
System.out.println("Rows updated: "+i);
System.out.println("Contents of the dispatches table after updating the records: ");
//检索数据
ResultSet rs = stmt.executeQuery("Select * from dispatches");
while(rs.next()) {
System.out.print("Name: "+rs.getString("ProductName")+", ");
System.out.print("Customer Name: "+rs.getString("CustomerName")+", ");
System.out.print("Dispatch Date: "+rs.getDate("DispatchDate")+", ");
System.out.print("Delivery Time: "+rs.getTime("DeliveryTime")+", ");
System.out.print("Price: "+rs.getInt("Price")+", ");
System.out.print("Location: "+rs.getString("Location"));
System.out.println();
}
}
}输出结果
Connection established...... Rows updated: 5 Contents of the dispatches table after updating the records: Name: Key-Board, Customer Name: Raja, Dispatch Date: 2019-09-01, Delivery Time: 11:00:00, Price: 10001, Location: Hyderabad Name: Earphones, Customer Name: Roja, Dispatch Date: 2019-05-01, Delivery Time: 11:00:00, Price: 5000, Location: Vishakhapatnam Name: Mouse, Customer Name: Puja, Dispatch Date: 2019-03-01, Delivery Time: 10:59:59, Price: 6000, Location: Vijayawada Name: Mobile, Customer Name: Vanaja, Dispatch Date: 2019-03-01, Delivery Time: 10:10:52, Price: 12001, Location: Chennai Name: Headset, Customer Name: Jalaja, Dispatch Date: 2019-04-06, Delivery Time: 11:08:59, Price: 9000, Location: Goa