如何使用JDBC API从Oracle数据库中现有表中删除记录?
您可以使用DELETE查询从数据库中的表中删除特定记录。
语法
DELETE FROM table_name WHERE [condition];
要使用JDBC API从表中删除记录,您需要:
注册驱动程序: 使用**DriverManager**类的**registerDriver()**方法注册驱动程序类。将驱动程序类名作为参数传递。
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。
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Statement接口的executeUpdate()方法执行查询。
让我们使用CREATE语句在Oracle数据库中创建一个名为**dispatches**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**dispatches**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');
下面的JDBC程序建立与Oracle数据库的连接,并从Dispatches表中删除名为Jalaja的客户的记录。
示例
import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; public class DeleteRecordsOracle { public static void main(String args[]) throws SQLException { //Registering the Driver DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver()); //Getting the connection String oracleUrl = "jdbc:oracle:thin:@localhost:1521/xe"; Connection con = DriverManager.getConnection(oracleUrl, "system", "password"); System.out.println("Connection established......"); //Creating the Statement Statement stmt = con.createStatement(); //Query to delete records String query = "Delete from dispatches where CUSTOMERNAME = 'Jalaja'"; int i = stmt.executeUpdate(query); System.out.println("Rows deleted: "+i); //Retrieving data ResultSet rs = stmt.executeQuery("Select * from dispatches"); System.out.println("Contents of the table after deleting the records: "); 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
Connection established...... Rows deleted: 1 Contents of the table after deleting 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
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