Shulou(Shulou.com)06/01 Report--

JDBC provides a standard for accessing a database is a series of interfaces that define a common way to access a database.

The implementation of JDBC is provided by various database vendors

Definition of JDBC interface

Database manufacturer's implementation of jdbc jar

Establish connection-send sql- to execute sql- return result-close connection

JDBC API (interface)

Connection between java.sql.Connection// encapsulation and database

Java.sql.Statement// encapsulates the execution of SQL statements

Jave.sql.ResultSet// encapsulates the result of DQL execution

Package jdbc;import java.sql.Connection;import java.sql.Driver;import java.sql.DriverManager;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;import oracle.jdbc.OracleDriver;public class OracleDemo01 {public static void main (String [] args) throws Exception {/ / implementation of loading JDBC / / Driver driver = new OracleDriver () Write / / DriverManager.registerDriver (driver) by yourself; / / load the class into the static fast memory and execute the above two items without having to write / / the code in the static block of the class will register Class.forName for Driver ("oracle.jdbc.OracleDriver") / / load the JDBC implementation with this / / create a connection / / call the getConnection method of DriverManager / / this method returns the object of the database vendor's implementation class of the Connection interface (because DriverManager has registered the database vendor's Driver information) String url = "jdbc:oracle : thin:@x1.zongxuan.online:1521:xx " String user = "scott"; String pass = "xxxxx"; Connection con = DriverManager.getConnection (url,user,pass) / / url is used to represent the connection information of the database (ip port database name) different database vendors have specific url formats and identities / / DriverManager will select different driver information according to this logo / / if you register at the same time Implementation of multiple database vendors / / user / / password / / System.out.println (con) / / execute the createStatement () method of SQL / / Connection to create the object Statement stmt = con.createStatement () of the Statement implementation class / / only DQL statements can be executed / / the return value is ResultSet / / transfer the SQl statement to the database for execution / / get the result data of the database transmission / / and encapsulate this data into a ResultSet object ResultSet rs = stmt.executeQuery ("select empno Ename name,sal from emp ") / / get the result while (rs.next ()) {/ / .next () cursor down System.out.println (rs.getString ("empno") + "," + rs.getString ("name") + "," + rs.getString ("sal"));} rs.close () / / close connection}} package jdbc;import java.sql.Connection;import java.sql.DriverManager;import java.sql.Statement;public class OracleDemo02 {public static void main (String [] args) throws Exception {Class.forName ("oracle.jdbc.OracleDriver") String url = "jdbc:oracle:thin:@x1.zongxuan.online:1521:xx"; String user= "scott"; String pass= "xxxxx"; Connection con = DriverManager.getConnection (url,user,pass); Statement stmt = con.createStatement () / / execute the DML statement insert delete update String sql = "insert into emp2 (empno,ename,sal,deptno) values"; int n = stmt.executeUpdate (sql); / / return an integer representation of the number of rows affected by the statement just now System.out.println (n); con.close ();}} package jdbc Import java.sql.Connection;import java.sql.DriverManager;import java.sql.Statement;public class OracleDemo03 {public static void main (String [] args) throws Exception {Class.forName ("oracle.jdbc.OracleDriver"); String url = "jdbc:oracle:thin:@x1.zongxuan.online:1521:xx"; String user = "scott"; String pass = "xxxxx" Connection con = DriverManager.getConnection (url,user,pass); Statement stmt = con.createStatement (); String sql = "delete from emp2 where ename='lmdtx'"; int n = stmt.executeUpdate (sql); System.out.println (n); con.close ();}}

There is a risk of being injected.

Name:a' or 'baked goods ba' or' b'='bselect ename,empno,sal from emp2 where ename ='a'or 'b'='b'package jdbc;import java.sql.Connection;import java.sql.DriverManager;import java.sql.ResultSet;import java.sql.Statement;import java.util.Scanner;public class OracleDemo04 {public static void main (String [] args) throws Exception {Scanner in = new Scanner (System.in) System.out.print ("name:"); String name = in.nextLine (); System.out.println (name); Class.forName ("oracle.jdbc.OracleDriver"); String url = "jdbc:oracle:thin:@x1.zongxuan.online:1521:xx"; String user = "scott" String pass = "xxxxx"; Connection con = DriverManager.getConnection (url,user,pass); Statement stat = con.createStatement (); String sql = "select ename,empno,sal from emp2 where ename ='" + name+ "'"; System.out.println (sql); ResultSet rs = stat.executeQuery (sql) While (rs.next ()) {System.out.println (rs.getString (1) + "," + rs.getInt (2) + "," + rs.getInt (3));} con.close ();}}

PreparedStatement interface (use this is good)

Improve efficiency

Prevent SQL Injection

1 create a connection

2PreparedStatement

PreparedStatement stmt = con.prepareStatement (sql)

3 stmt.setString (1, "xxx")

Stmt.setInt (1123)

Package jdbc;import java.io.BufferedReader;import java.io.InputStreamReader;import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;public class OracleDemo05 {public static void main (String [] args) throws Exception {BufferedReader br = new BufferedReader (new InputStreamReader (System.in)); System.out.println ("name:"); String name = br.readLine () Class.forName ("oracle.jdbc.OracleDriver"); String url = "jdbc:oracle:thin:@x1.zongxuan.online:1521:xx"; String user = "scott"; String pass = "xxxxx"; Connection con = DriverManager.getConnection (url,user,pass); String sql = "select empno,ename,sal from emp2 where ename=?" PreparedStatement stmt = con.prepareStatement (sql); / / set the value of the first question mark in sql to the string stmt.setString (1jue name); ResultSet rs = stmt.executeQuery () While (rs.next ()) {System.out.println (rs.getInt (1) + "," + rs.getString (2) + "," + rs.getInt (3));} con.close ();}} package jdbc;import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement Public class OracleDemo06 {public static void main (String [] args) throws Exception {Class.forName ("oracle.jdbc.OracleDriver"); String url = "jdbc:oracle:thin:@x1.zongxuan.online:1521:xx"; String user = "scott"; String pass = "xxxxx"; Connection con = DriverManager.getConnection (url,user,pass) String sql = "insert into emp2 (empno,ename) values (?,?)"; PreparedStatement stmt = con.prepareStatement (sql); int n = 0; for (int I = 1000

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