1.使用jdbc连接数据库：
a.导入驱动jar包
b.Class.forName(DRIVER);
// 2.建立连接
con = DriverManager.getConnection(URL, USERNAME, PWD);
2.增、删、改：（只要修改sql就可实现）
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
public class UpadateTest {
public static final String DRIVER = "com.mysql.jdbc.Driver";
public static final String URL = "jdbc:mysql://localhost:3306/petstore";
public static final String USERNAME = "root";
public static final String PWD = "root";
public static void main(String[] args) {
Connection con = null;
Statement statement = null;
try {
Class.forName(DRIVER);
con = DriverManager.getConnection(URL, USERNAME, PWD);
statement = con.createStatement();
String sql = "update pet set name=‘毛毛‘ where id=2";
int result = statement.executeUpdate(sql);//增删改
if (result > 0) {
System.out.println("修改成功");
} else {
System.out.println("修改失败");
}
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}finally{
try {
statement.close();
con.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
3.查询：
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class QueryTest {
public static final String DRIVER = "com.mysql.jdbc.Driver";
public static final String URL = "jdbc:mysql://localhost:3306/petstore";
public static final String USERNAME = "root";
public static final String PWD = "root";
public static void main(String[] args) {
Connection con = null;
Statement statement = null;
ResultSet rs=null;
try {
Class.forName(DRIVER);
con = DriverManager.getConnection(URL, USERNAME, PWD);
statement = con.createStatement();
String sql = "select * from pet";
rs = statement.executeQuery(sql);
while (rs.next()) {
System.out.print(rs.getInt(1)+"\t");
System.out.print(rs.getString(2)+"\t");
System.out.print(rs.getInt(3)+"\t");
System.out.print(rs.getInt(4)+"\t");
System.out.print(rs.getString(5)+"\n");
}
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}finally{
try {
rs.close();
statement.close();
con.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
4.statement的方法的区别：
execute 不常用 返回值是boolean类型，true指返回结果集
executeUpdate 增、删、改 返回int类型，指受影响的行数
executeQuery 查 返回ResultSet类型，指结果集
5.prepareStatement避免sql注入异常
使用方式：
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
public class PrepTest {
public static final String DRIVER = "com.mysql.jdbc.Driver";
public static final String URL = "jdbc:mysql://localhost:3306/petstore";
public static final String USERNAME = "root";
public static final String PWD = "root";
public static void main(String[] args) {
Connection con = null;
PreparedStatement ps = null;
ResultSet rs = null;
List<Master> masterlst = new ArrayList<Master>();
try {
// 1加载驱动
Class.forName(DRIVER);
// 2创建连接
con = DriverManager.getConnection(URL, USERNAME, PWD);
// 3声明Sql
// StringBuffer sql = new StringBuffer("select * from master where 1=1 ");
// sql.append("and name=? ");
// sql.append("and money=?");
String sql="select * from master ";
// 4.创建PreparedStatement对象
ps = con.prepareStatement(sql);
// 5.传参数
// ps.setString(1, "李");
// ps.setInt(2, 100);
// 6.执行sql
rs = ps.executeQuery();
// 7遍历显示
while (rs.next()) {
Master m = new Master();
m.setId(rs.getInt(1));
m.setName(rs.getString(2));
m.setPassword(rs.getString(3));
m.setMoney(rs.getInt(4));
masterlst.add(m);
}
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
} finally {
// 8.关闭对象//由内到外关闭
try {
rs.close();
ps.close();
con.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
System.out.println("查询结果：");
for (Master m:masterlst) {
System.out.println(m.getId()+"\t"+m.getName()+"\t"+m.getPassword()+"\t"+m.getMoney());
}
}
}