Java ResultSet deleteRow() 方法带示例
当我们执行某些 SQL 查询(通常是 SELECT 查询)时,它们会返回表格数据。
java.sql.ResultSet 接口表示 SQL 语句返回的此类表格数据。
即ResultSet 对象持有由执行查询数据库语句(通常是 Statement 接口的 executeQuery() 方法)的方法返回的表格数据。
ResultSet 对象有一个游标/指针,指向当前行。最初这个游标位于第一行之前。
ResultSet 接口的 deleteRow() 方法从 ResultSet 对象和表中删除当前行。
rs.deleteRow();
使用 CREATE 语句在 MySQL 数据库中创建一个名为 MyPlayers 的表,如下所示:
CREATE TABLE MyPlayers( ID INT, First_Name VARCHAR(255), Last_Name VARCHAR(255), Date_Of_Birth date, Place_Of_Birth VARCHAR(255), Country VARCHAR(255), PRIMARY KEY (ID) );
现在,我们将使用 INSERT 语句在 MyPlayers 表中插入 7 条记录
insert into MyPlayers values(1, 'Shikhar', 'Dhawan', DATE('1981-12-05'), 'Delhi', 'India'); insert into MyPlayers values(2, 'Jonathan', 'Trott', DATE('1981-04-22'), 'CapeTown', 'SouthAfrica'); insert into MyPlayers values(3, 'Kumara', 'Sangakkara', DATE('1977-10-27'), 'Matale', 'Srilanka'); insert into MyPlayers values(4, 'Virat', 'Kohli', DATE('1988-11-05'), 'Delhi', 'India'); insert into MyPlayers values(5, 'Rohit', 'Sharma', DATE('1987-04-30'), 'Nagpur', 'India'); insert into MyPlayers values(6, 'Ravindra', 'Jadeja', DATE('1988-12-06'), 'Nagpur', 'India'); insert into MyPlayers values(7, 'James', 'Anderson', DATE('1982-06-30'), 'Burnley', 'England');
下面的 JDBC 程序建立与数据库的连接,从 Myplayers 表中删除最后一条记录,并在删除操作后打印表中的内容。
示例
import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; public class ResultSet_deleteRow { public static void main(String args[]) throws SQLException { //Registering the Driver DriverManager.registerDriver(new com.mysql.jdbc.Driver()); //Getting the connection String mysqlUrl = "jdbc:mysql://127.0.0.1/mydatabase"; Connection con = DriverManager.getConnection(mysqlUrl, "root", "password"); System.out.println("Connection established......"); //Creating the Statement Statement stmt = con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_UPDATABLE); //Query to retrieve records String query = "Select * from MyPlayers"; //Executing the query ResultSet rs = stmt.executeQuery(query); //Moving the pointer to last row rs.last(); //Removing the current row from the ResultSet rs.deleteRow(); rs.beforeFirst(); System.out.println("Contents of the table after deleting a row: "); while(rs.next()) { System.out.print("ID: "+rs.getInt("ID")+", "); System.out.print("Name: "+rs.getString("First_Name")+", "); System.out.print("Age: "+rs.getString("Last_Name")+", "); System.out.print("Salary: "+rs.getDate("Date_Of_Birth")+", "); System.out.print("Country: "+rs.getString("Place_Of_Birth")+", "); System.out.print("Address: "+rs.getString("Country")); System.out.println(); } } }
输出
Connection established...... Contents of the table after deleting a row: Connection established...... Contents of the table after deleting a row: ID: 1, Name: Shikhar, Age: Dhawan, Salary: 1981-12-05, Country: Delhi, Address: India ID: 2, Name: Jonathan, Age: Trott, Salary: 1981-04-22, Country: CapeTown, Address: SouthAfrica ID: 3, Name: Kumara, Age: Sangakkara, Salary: 1977-10-27, Country: Matale, Address: Srilanka ID: 4, Name: Virat, Age: Kohli, Salary: 1988-11-05, Country: Mumbai, Address: India ID: 5, Name: Rohit, Age: Sharma, Salary: 1987-04-30, Country: Nagpur, Address: India ID: 6, Name: Ravindra, Age: Jadeja, Salary: 1988-12-06, Country: Nagpur, Address: India
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