Sample code for connecting to mysql database in myeclipse_MySQL

1. Environment configuration

Download address: The code is as follows:

Connection connectMySQL = DriverManager.getConnection("jdbc:mysql://localhost:3306/myuser","root" ,"root" );

4) Create Statement object: The Statement class is mainly an object used to execute static SQL statements and return the results it generates. A Statement object can be created through the createStatement() method of the Connection object. For example: Statement statament = connection.createStatement(); The specific example code to create a Statement object is as follows:

The code is as follows:

Statement statamentMySQL =connectMySQL.createStatement();

In addition, under normal circumstances, PreparedStatement can be used to code Statement, because PreparedStatement can prevent SQL injection attacks, prevent database buffer pool overflow, and improve code readability and maintainability. The specific example of creating PreparedStatement code is as follows:

The code is as follows:

String sql = "Select title, year_made from movies where year_made >= ? and year_made <= ?";
PreparedStatement ps =connectMySQL.prepareStatement(sql);

5) Call the relevant methods of the Statement object to execute the corresponding SQL statement: use the execuUpdate() method to update data, including insertion and deletion operations, such as the code to insert a piece of data into the staff table:

The code is as follows:

statement.excuteUpdate( "INSERT INTO staff(name, age, sex,address, depart, worklen,wage)" + " VALUES ('Tom1', 321, 'M', 'china',' Personnel','3','3000' ) ") ;

If using PreparedStatement, then:

prest.setInt(1,1980); //表示第1个参数为1980
prest.setInt(2,2004);
ResultSet rs = prest.executeQuery();

Query the data by calling the executeQuery() method of the Statement object, and the query result will get a ResultSet object. ResultSet represents the collection of data returned after executing the query database. The ResultSet object has a pointer that can point to the current data row. Through the next() method of the object, the pointer points to the next row, and then the data is taken out by column number or field name. If the next() method returns null, it means that there is no data in the next row. The sample code is as follows:

The code is as follows:

ResultSet resultSet = statement.executeQuery( "select * from staff" );

6) Close the database connection: When you have finished using the database or do not need to access the database, close the data connection in a timely manner through the close() method of Connection.

3. Test code

After configuring the environment, you can write code to test whether the connection can be connected!

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
 
public class TestMysqlConn {
 public static void main(String[] args) {
  Connection con; 
  Statement stmt; 
  ResultSet rs;
   
  try {
   Class.forName("com.mysql.jdbc.Driver").newInstance(); 
 
　　　　　　 //test为数据库名，_test为表名。_test表中有三个字段：id name description
   con = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/test","root","root");
 
   stmt = con.createStatement(); 
 
   rs = stmt.executeQuery("select * from _test"); 
    
   while(rs.next()){
   int num = rs.getInt("id");
   String name = rs.getString("name");
   String des = rs.getString("description");
   System.out.println(num + " " + name + " " + des);
  }
   stmt.close();
  conn.close();
  } catch (Exception e) {
   e.printStackTrace();
   System.out.println("连接失败");
  }
 }
}

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