PreparedStatement与Statement

Statement database operation:
CRUD: using the executeUpdate ();
query: Use the executeQuery ();

The ResultSet: * Save result set from XXX SELECT
Next (): cursor downward, determines whether the next data; to true / to false
Previous (): to true / to false
getXxx (field names | position): Get a specific field value of

package jdbc;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;


public class JDBCDemo {
    private final String URL="jdbc:mysql://localhost:3306/java?useSSL=false";
    private final String USERNAME = "root";
    private final String PASSWORD = "123456";
    public void update(){//实现增删改
        Connection connection = null; 
        The Statement stmt = null ;
         the try {
             // A driving introduced. 
            The Class.forName ( "com.mysql.jdbc.Driver" );
             // B establish a connection to a database. 
            Connection =   the DriverManager.getConnection (the URL, USERNAME, PASSWORD);
             // . C transmission sql, additions and deletions performed, check 
            stmt = Connection.createStatement ();
             // String SQL = "INSERT INTO Book (name,. price) values ( 'novel', 50)";
             // String = SQL " update book set name = 'scientific' the WHERE the above mentioned id = 17 "; 
            String SQL =" Book the Delete from the WHERE the above mentioned id = 19 " ;
            //d.执行sql语句
            stmt.executeUpdate(sql);
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally{
            try{
            if(stmt!=null)           stmt.close();
            if(connection!=null)    connection.close();
        }catch(SQLException e){
            e.printStackTrace();
            }
        }
    }
    public void query(){//实现查询
        Connection = Connection null ; 
        the Statement stmt = null ; 
        the ResultSet RS = null ;
         the try {
             // A driving introduced. 
            The Class.forName ( "com.mysql.jdbc.Driver" );
             // . B establish a connection to a database 
            Connection =   the DriverManager. getConnection (the URL of, USERNAME, PASSWORD);
             // . c send sql, additions and deletions to perform, check 
            stmt = Connection.createStatement (); 
            String SQL = "Book from the SELECT *" ;
             //SQL execution [CRUD executeUpdate (), query the executeQuery ()] 
            RS = stmt.executeQuery (SQL);
             // process result 
            the while (rs.next ()) { // determines whether there is a next line data 
                String na = rs.getString ( "name" ); 
                String PRI = rs.getString ( ". price" ); 
                System.out.println (Na + "-" + PRI); 
            } 
        } the catch (Exception E) {
             // the TODO Auto Block the catch-Generated 
            e.printStackTrace (); 
        } the finally {
             the try {
                 IF(rs!=null)            rs.close();
                if(stmt!=null)           stmt.close();
                if(connection!=null)    connection.close();
        }catch(SQLException e){
            e.printStackTrace();
            }
        }
    }
    public static void main(String[] args) {
        JDBCDemo j = new JDBCDemo();
        //j.update();
        j.query();
    }
}

PreparedStatement operation of the database:

public interface PreparedStatement extends Statement
Thus
CRUD: executeUpdate ()
Query: the executeQuery ();
- furthermore
assignment setXxx ();

package jdbc;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class JDBCPreparedStatement {
    private final String URL="jdbc:mysql://localhost:3306/java?useSSL=false";
    private final String USERNAME = "root";
    private final String PASSWORD = "123456";
    public void update(){//实现增删改
        Connection connection = null ; 
        the PreparedStatement pstmt = null ;
         the try {
             // A driving introduced. 
            the Class.forName ( "com.mysql.jdbc.Driver" );
             // B establish a connection to a database. 
            Connection =   the DriverManager.getConnection (the URL, USERNAME, PASSWORD) ;
             // . c send sql, additions and deletions to perform, check 
            String SQL = "INSERT INTO Book values (,,???)" ; 
            pstmt = Connection.prepareStatement (SQL); 
            
            pstmt.setString ( 1, "next door" ); 
            pstmt.setString ( 2, "56 is" ); 
            pstmt.setInt (3, 21);
            //String sql = "insert into book(name,price) values('小说',50)";
            //String sql = "update book set name='科学' where id=17";
            
            pstmt.executeUpdate();
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally{
            try{
            if(pstmt!=null)           pstmt.close();
            if(connection!=null)    connection.close();
        }catch(SQLException E) { 
            e.printStackTrace (); 
            } 
        } 
    } 
    public  void Query () { 
        Connection Connection = null ; 
        the PreparedStatement pstmt = null ; 
        the ResultSet RS = null ;
         the try {
             // A driving introduced. 
            The Class.forName ( "COM. mysql.jdbc.Driver " );
             // . B establish a connection to a database 
            connection =   the DriverManager.getConnection (the URL, USERNAME, PASSWORD);
             // . C transmission sql, additions and deletions performed, search
            SQL = String "from the SELECT * Book the WHERE the above mentioned id =?" ; 
            Pstmt = Connection.prepareStatement (SQL); 
            
            pstmt.setInt ( 1, 21 );
             // execute sql [CRUD executeUpdate (), query executeQuery ()] 
            rs = pstmt.executeQuery ();
             // process result 
            the while (rs.next ()) { // determines whether there is a next line data 
                String = Na rs.getString ( "name" ); 
                String PRI = rs.getString ( ". price" ) ; 
                System.out.println (Na + "-" + PRI); 
            } 
        } the catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally{
            try{
                if(rs!=null)            rs.close();
                if(pstmt!=null)           pstmt.close();
                if(connection!=null)    connection.close();
        }catch(SQLException e){
            e.printStackTrace();
            }
        }
    }
    public static void main(String[] args) {
        JDBCPreparedStatement j = new JDBCPreparedStatement();
        /*j.update();*/
        j.query();
    }
}

PreparedStatement and Statement of differences in the use of:

Of Statement:
1, defined SQL

String sql =" insert into book(name,price) values('小说',50) " ;
2、stmt.executeUpdate(sql);

PreparedStatement:

1, sql defined

String sql =" insert into book(name,price) values(？,？,?) " ;
pstmt = connection.prepareStatement(sql);//预编译SQL
pstmt.setString(1, "隔壁");

pstmt.setString(2, "56");
pstmt.setInt(3, 21);

2、 pstmt.executeUpdate();