What is executeUpdate

executeUpdate is a method in Java that is used to execute SQL statements and update data in the database. It is usually used to execute INSERT, UPDATE and DELETE statements, and can insert, update and delete tables in the database. It is a method of Statement interface and PreparedStatement interface and can be used in the implementation classes of these two interfaces. It returns an integer value representing the number of affected rows in the database.

executeUpdate is a method in Java that is used to execute SQL statements and update data in the database. It is usually used to execute INSERT, UPDATE and DELETE statements, and can insert, update and delete tables in the database.

The executeUpdate method is a method of the Statement interface and the PreparedStatement interface and can be used in the implementation classes of these two interfaces. It returns an integer value representing the number of affected rows in the database.

Before using the executeUpdate method, you need to establish a database connection and create a Statement object or PreparedStatement object. Statement objects are used to execute static SQL statements, while PreparedStatement objects are used to execute dynamic SQL statements.

The syntax of the executeUpdate method is as follows:

int executeUpdate(String sql) throws SQLException

Among them, the sql parameter is the SQL statement to be executed. The executeUpdate method will send the SQL statement to the database for execution and return the number of affected rows.

When executing an INSERT statement, the executeUpdate method returns the number of inserted rows. When executing an UPDATE or DELETE statement, the executeUpdate method returns the number of rows updated or deleted.

The following is an example of using the executeUpdate method to insert data:

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;
import java.sql.SQLException;
public class InsertData {
    public static void main(String[] args) {
        // 建立数据库连接
        try {
            Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/mydatabase", "username", "password");
            
            // 创建Statement对象
            Statement stmt = conn.createStatement();
            
            // 定义要执行的SQL语句
            String sql = "INSERT INTO student (id, name, age) VALUES (1, 'John', 20)";
            
            // 执行SQL语句并更新数据库
            int rows = stmt.executeUpdate(sql);
            
            System.out.println("插入了 " + rows + " 行数据");
            
            // 关闭连接
            stmt.close();
            conn.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

In the above example, the connection to the database is first established, and then the Statement object is created. Then the insert statement to be executed is defined, the statement is sent to the database for execution through the executeUpdate method, and the number of affected rows is returned. Finally close the connection.

In short, the executeUpdate method is a method in Java used to execute SQL statements and update data in the database. It can be used to execute INSERT, UPDATE and DELETE statements and return the number of affected rows. Through this method, you can easily perform insert, update and delete operations on the database.

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