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📜  Apache Commons DBUtils-删除查询

📅  最后修改于: 2020-11-18 08:08:34             🧑  作者: Mango

下面的示例将演示如何在DBUtils的帮助下使用Delete查询删除记录。我们将删除员工表中的一条记录。

句法

String deleteQuery = "DELETE FROM employees WHERE id=?";
int deletedRecords = queryRunner.delete(conn, deleteQuery, 33,104);

哪里，

  • deleteQuery-删除具有占位符的查询。

  • queryRunner -QueryRunner对象，用于删除数据库中的员工对象。

为了理解与DBUtils有关的上述概念，让我们编写一个示例，该示例将运行删除查询。为了编写示例，让我们创建一个示例应用程序。

Step Description
1 Update the file MainApp.java created under chapter DBUtils – First Application.
2 Compile and run the application as explained below.

以下是Employee.java的内容。

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);
      }  
   }
}

创建完源文件后，让我们运行该应用程序。如果您的应用程序一切正常，它将打印以下消息。

1 record(s) deleted.