以下示例将演示如何在DBUtils的帮助下使用Delete查询删除记录.我们将删除Employees表中的记录.
String deleteQuery = "DELETE FROM employees WHERE id=?"; int deletedRecords = queryRunner.delete(conn, deleteQuery, 33,104);
其中,
deleteQuery : 删除具有占位符的查询.
queryRunner : QueryRunner对象删除数据库中的员工对象.
为了理解上述与DBUtils相关的概念,让我们编写一个示例,运行删除查询.要编写我们的示例,让我们创建一个示例应用程序.
Step | 描述 |
---|---|
1 | 更新在DBUtils的MainApp.java . |
2 | 编译并运行应用程序,如下所述. |
以下是
public class Employee { private int id; private int age; private String first; private String last; public int getId() { return id; } public void setId(int id) { this.id = id; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public String getFirst() { return first; } public void setFirst(String first) { this.first = first; } public String getLast() { return last; } public void setLast(String last) { this.last = last; } }
以下是 MainApp.java 文件的内容.
import java.sql.Connection; import java.sql.DriverManager; import java.sql.SQLException; import org.apache.commons.dbutils.DbUtils; import org.apache.commons.dbutils.QueryRunner; public class MainApp { // JDBC driver name and database URL static final String JDBC_DRIVER = "com.mysql.jdbc.Driver"; static final String DB_URL = "jdbc:mysql://localhost:3306/emp"; // Database credentials static final String USER = "root"; static final String PASS = "admin"; public static void main(String[] args) throws SQLException { Connection conn = null; QueryRunner queryRunner = new QueryRunner(); DbUtils.loadDriver(JDBC_DRIVER); conn = DriverManager.getConnection(DB_URL, USER, PASS); try { int deletedRecords = queryRunner.update(conn, "DELETE from employees WHERE id=?", 104); System.out.println(deletedRecords + " record(s) deleted."); } finally { DbUtils.close(conn); } } }
创建源文件后,让我们运行应用程序.如果您的应用程序一切正常,它将打印以下消息.
1 record(s) deleted.