Apakah perbezaan antara kaedah execute(), executeQuery() dan executeUpdate() dalam JDBC?

Setelah anda mencipta objek pernyataan, anda boleh melaksanakannya menggunakan salah satu kaedah execute(), executeUpdate(), dan executeQuery() bagi antara muka Penyata.

execute() kaedah: Kaedah ini digunakan untuk melaksanakan pernyataan SQL DDL Ia mengembalikan nilai Boolean yang menyatakan sama ada objek ResultSet boleh diambil.

Contoh

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
public class Example {
   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://localhost/sampleDB";
      Connection con = DriverManager.getConnection(mysqlUrl, "root", "password");
      System.out.println("Connection established......");
      //Creating the Statement
      Statement stmt = con.createStatement();

      //Executing the statement
      String createTable = "CREATE TABLE Employee( "
         + "Name VARCHAR(255), "
         + "Salary INT NOT NULL, "
         + "Location VARCHAR(255))";
      boolean bool = stmt.execute(createTable);

      System.out.println(bool);
   }
}

Output

Connection established......
false

executeUpdate():#🎜 digunakan, digunakan untuk melakukan insert memadam dan lain-lain kenyataan. Ia mengembalikan nilai integer yang mewakili bilangan baris yang terjejas.

Contoh

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
public class ExecuteUpdateExample {
   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://localhost/sampleDB";
      Connection con = DriverManager.getConnection(mysqlUrl, "root", "password");
      System.out.println("Connection established......");
      //Creating the Statement
      Statement stmt = con.createStatement();
     
      String insertData = "INSERT INTO Employee("
         + "Name, Salary, Location) VALUES "
         + "('Amit', 30000, 'Hyderabad'), "
         + "('Kalyan', 40000, 'Vishakhapatnam'), "
         + "('Renuka', 50000, 'Delhi'), "
         + "('Archana', 15000, 'Mumbai')";

      int i = stmt.executeUpdate(insertData);
      System.out.println("Rows inserted: "+i);
   }
}

Output

Connection established......
Rows inserted: 4

executeQuery(): #🎜🎜 yang digunakan untuk laksanakan pernyataan ini data (cth. pilih). Ia mengembalikan objek kelas ResultSet. Contoh

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class ExecuteQueryExample {
   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://localhost/sampleDB";
      Connection con = DriverManager.getConnection(mysqlUrl, "root", "password");
      System.out.println("Connection established......");
      //Creating the Statement
      Statement stmt = con.createStatement();

      //Retrieving data
      ResultSet rs = stmt.executeQuery("Select *from Employee");

      while(rs.next()) {
         System.out.print("Name: "+rs.getString("Name")+", ");
         System.out.print("Salary: "+rs.getInt("Salary")+", ");
         System.out.print("City: "+rs.getString("Location"));
         System.out.println();
      }
   }
}

Output

Connection established......
Name: Amit, Salary: 30000, City: Hyderabad
Name: Kalyan, Salary: 40000, City: Vishakhapatnam
Name: Renuka, Salary: 50000, City: Delhi
Name: Archana, Salary: 15000, City: Mumbai

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