JDBC advanced

JDBC  Advanced

precompile  PreparedStatement

PreparedStatement  Class inherits from  Statement  class , stay  JDBC  Used to replace the former in development . There are two advantages ：

• But for  SQL  Statement precompiling , It can be modified flexibly  SQL  sentence , Improve development efficiency .

• Escape the single quotation mark entered by the user , Prevent malicious Injection , Protect database security .

Connection connection = DriverManager.getConnection();
String sql = "INSERT INTO test(id,name) VALUES (?,?)";
PreparedStatement stmt = connection.preparedStatement(sql); //  Create objects and precompile
stmt.setInt(1, 755); //  In the first placeholder (?) Insert number in position
stmt.setString(2, "MrJoker"); //  In the second placeholder (?) Position insert string
stmt.executeUpdate(); //  Update and execute Copy to clipboardErrorCopied


The batch  executeBath

PreparedStatement  Class can pass through  executeBath  Method batch processing  SQL  sentence , Further improve efficiency . The return value is a  int[]  Array .

Connection connection = DriverManager.getConnection();
String sql = "INSERT INTO test(id,name) VALUES (?,?)";
PreparedStatement stmt = connection.prepareStatement(sql);
for (int i = 1; i <= 1000; i++) {
 stmt.setInt(1, i);
 stmt.setString(2, (i + &quot; Soldier No &quot;));
 stmt.addBatch(); //  Statement is added to the batch sequence
}
preparedStatement.executeBatch(); //  Statement is sent to the database for batch processing
preparedStatement.clearBatch(); //  Empty batch sequence Copy to clipboardErrorCopied


Large text and binary data

• clob  For storing large text

• blob Used to store binary data

JDBC  Example

//  Apply to  JDK 1.8  Later versions

import java.sql.*; 

public class MySQLTest{

 static final String JDBC_DRIVER = "com.mysql.cj.jdbc.Driver"; 
 static final String DB_URL = "jdbc:mysql://localhost:3306/RUNOOB?useSSL=false&serverTimezone=UTC";
 static final String USER = "root"; 
 static final String PASS = "123456";

 public static void useMethod（）{
 Connection conn = null; 
 PreparedStatement stmt = null; 
 try{
 Class.forName(JDBC_DRIVER); 
 conn = DriverManager.getConnection(DB_URL,USER,PASS); 
 stmt = conn.preparedStatement("SELECT id, name, url FROM websites"); 
 ResultSet rs = stmt.executeQuery(); 
 while(rs.next()){
 System.out.println(rs.getString("area_id")); 
 }
 rs.close(); 
 stmt.close(); 
 conn.close(); 
 }catch(SQLException se){ //  Handle  JDBC  error
 se.printStackTrace(); 
 }catch(Exception e){ //  Handle  Class.forName  error
 e.printStackTrace(); 
 }finally{ 
 try{ 
 if(stmt != null) stmt.close(); 
 }catch(SQLException se2){}
 try{
 if(conn != null) conn.close(); 
 }catch(SQLException se){} 
 }
 }
}