Insérer des données et si déjà inséré, puis mettez à jour en SQL

L'instruction SQL standard pour insert code> (si nouveau) ou update code> (si existe) est appelé fusion code> strong> .

Puisque vous n'avez pas précisé quelle dialecte DBMS vous posez des questions, je vous référerai à l'article Wikipedia " fusion (SQL) ", qui couvre la plupart des dialectes SGBM. Résumé: P>

MERGE INTO tablename USING table_reference ON (condition)
WHEN MATCHED THEN
  UPDATE SET column1 = value1 [, column2 = value2 ...]
WHEN NOT MATCHED THEN
  INSERT (column1 [, column2 ...]) VALUES (value1 [, value2 ...])

package com.stackwork;

//STEP 1. Import required packages
import java.sql.*;
import java.util.Scanner;

public class Updation {
   // JDBC driver name and database URL
   static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";  
   static final String DB_URL = "jdbc:mysql://localhost/Employee";

   //  Database credentials
   static final String USER = "root";
   static final String PASS = "admin";
   private static Scanner sc;

   public static void main(String[] args) {
   Connection conn = null;
   Statement stmt = null;
   try{
      //STEP 2: Register JDBC driver
      Class.forName("com.mysql.jdbc.Driver");
      //STEP 3: Open a connection
      System.out.println("Connecting to database...");
      conn = DriverManager.getConnection(DB_URL,USER,PASS);
      //STEP 4: Execute a query
      System.out.println("Creating statement...");
      stmt = conn.createStatement();
      String sql;
      //STEP 5: Get the employee_id for whom data need to be updated/inserted
      sc = new Scanner(System.in);
      System.out.println("Enter the Employee_id for the record to be updated or inserted");
      int Emp_idvalue=sc.nextInt();
      sql = "SELECT * FROM EmployeeDetails where Emp_id="+Emp_idvalue;
      ResultSet rs = stmt.executeQuery(sql);
      if (!rs.next())
      {
          //STEP 6: If the previous details is not there ,then the details will be inserted newly
          System.out.println("Enter the name to be inserted");
          String Emp_namevalue =sc.next();
          System.out.println("Enter the address to be inserted");
          String Emp_addvalue =sc.next();
          System.out.println("Enter the role to be inserted");
          String Emp_rolevalue =sc.next();
          PreparedStatement ps = conn
                    .prepareStatement("insert into EmployeeDetails values(?,?,?,?)");
            ps.setString(2, Emp_namevalue);
            ps.setString(3, Emp_addvalue);
            ps.setString(4, Emp_rolevalue);
            ps.setInt(1, Emp_idvalue);
            ps.executeUpdate();
            System.out.println("Inserted successfully");
      }
      else
      {
        //STEP 7: If the previous details is  there ,then the details will be updated 
          System.out.println("Enter the name to be updated");
          String Emp_namevalue =sc.next();
          System.out.println("Enter the address to be updated");
          String Emp_addvalue =sc.next();
          System.out.println("Enter the role to be updated");
          String Emp_rolevalue =sc.next();
          String updateQuery = "update EmployeeDetails set Emp_id=?,Emp_name=?, Emp_address=?, Emp_role=? where Emp_id='"
                    + Emp_idvalue + "'";
            PreparedStatement ps1 = conn.prepareStatement(updateQuery);
            ps1.setString(2, Emp_namevalue);
            ps1.setString(3, Emp_addvalue);
            ps1.setString(4, Emp_rolevalue);
            ps1.setInt(1, Emp_idvalue);
            ps1.executeUpdate();    
            System.out.println("updated successfully");

      }
      //Clean-up environment
      rs.close();
      stmt.close();
      conn.close();
   }catch(SQLException se){
      //Handle errors for JDBC
      se.printStackTrace();

   }catch(Exception e){
      //Handle errors for Class.forName
      e.printStackTrace();
  }
}
}