Dbutils 简明教程
Apache Commons DBUtils - Delete Query
下面的示例将演示如何借助 DBUtils 使用删除查询删除记录。我们将删除 Employees 表中的记录。
The following example will demonstrate how to delete a record using Delete query with the help of DBUtils. We will delete a record in Employees Table.
Syntax
删除查询的语法如下所示 −
The syntax for delete query is mentioned below −
String deleteQuery = "DELETE FROM employees WHERE id=?";
int deletedRecords = queryRunner.delete(conn, deleteQuery, 33,104);
其中,
Where,
-
deleteQuery − DELETE query having placeholders.
-
queryRunner − QueryRunner object to delete employee object in database.
为了了解与 DBUtils 相关的上述概念,让我们编写一个将运行删除查询的示例。为了编写我们的示例,让我们创建一个示例应用程序。
To understand the above-mentioned concepts related to DBUtils, let us write an example which will run a delete query. To write our example, let us create a sample application.
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。
Following is the content of the Employee.java.
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。
Following is the content of the MainApp.java file.
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);
}
}
}
一旦完成创建源文件,我们就来运行应用程序。如果你的应用程序一切正常,它将打印出以下消息 −
Once you are done creating the source files, let us run the application. If everything is fine with your application, it will print the following message −
1 record(s) deleted.