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JavaEE学习之jdbc基础认识
JDBC的定义:
Java Data Base Connectivity,java数据库连接;是一种用于执行SQL语句的Java API;
JDBC的操作步骤:
1.注册驱动
Class.forName();
2.获取连接
Connection xxx=DriverManager.getConnection();
3.编写sql
String sql=“ ”;
4.创建预编译的语句执行者
prepareStatement yyy=xxx.prepareStatement(sql,username,password);
5.设置参数
yyy.getString ()或者yyy.getInt();
6.执行查询
查询操作
yyy.executeQuery();
增删改操作
yyy.executeUpdate();
7.释放资源
???.close();
案例:
1 package cn.it.jdbc; 2 3 import java.sql.Connection; 4 import java.sql.DriverManager; 5 import java.sql.PreparedStatement; 6 import java.sql.ResultSet; 7 import java.sql.SQLException; 8 import java.sql.Statement; 9 10 import org.junit.Test; 11 12 import com.jdbc.utlis.jdbcUtils; 13 import com.jdbc.utlis.jdbcUtilsDemo; 14 15 public class helloDemo { 16 @Test 17 public void Myjdbc() throws ClassNotFoundException, SQLException { 18 // 1.注册驱动 19 Class.forName("com.mysql.jdbc.Driver"); 20 // 2.获取连接 21 Connection connection = DriverManager.getConnection( 22 "jdbc:mysql://localhost:3306/day01", "root", "root"); 23 // 3.编写sql 24 String sql = "select * from user"; 25 // 4.创建语句执行者 26 PreparedStatement statement = connection.prepareStatement(sql); 27 // 5.设置参数 28 29 // 6.执行sql语句 30 ResultSet resultSet = statement.executeQuery(); 31 // 7.遍历结果 32 while (resultSet.next()) { 33 System.out.println(resultSet.getString("id") + "----" 34 + resultSet.getString("username")); 35 36 } 37 resultSet.close(); 38 statement.close(); 39 connection.close(); 40 } 41 42 // 测试jdbcUtils测试方法 43 @Test 44 public void Utils() { 45 Connection connection = null; 46 PreparedStatement statement = null; 47 48 // 获取连接 49 try { 50 connection = jdbcUtils.getConnection(); 51 // 编写SQL语句 52 String sql = "INSERT INTO user VALUES(?,?)"; 53 // 语句预编译 54 statement = connection.prepareStatement(sql); 55 // 设置参数 56 statement.setInt(1, 5); 57 statement.setString(2, "小明"); 58 // 执行SQL 59 int i = statement.executeUpdate(); 60 // 判断语句是否执行成功 61 if (i == 1) { 62 System.out.println("OK!!!"); 63 } else { 64 System.out.println("NO!!!"); 65 } 66 67 } catch (ClassNotFoundException e) { 68 // TODO Auto-generated catch block 69 e.printStackTrace(); 70 } catch (SQLException e) { 71 // TODO Auto-generated catch block 72 e.printStackTrace(); 73 } finally { 74 jdbcUtils.closeStatent(statement); 75 jdbcUtils.closeConn(connection); 76 77 } 78 79 } 80 81 // 更新操作 82 @Test 83 public void update() { 84 Connection connection = null; 85 PreparedStatement statement = null; 86 try { 87 // 注册驱动 88 Class.forName("com.mysql.jdbc.Driver"); 89 // 获取连接 90 connection = DriverManager.getConnection( 91 "jdbc:mysql://localhost:3306/day01", "root", "root"); 92 // sq1语句 93 String sql = " UPDATE user SET username=? where id=? "; 94 // 创建语句执行者 95 statement = connection.prepareStatement(sql); 96 // 设置参数 97 statement.setString(1, "尔康"); 98 statement.setInt(2, 6); 99 // 执行sql语句 100 statement.executeUpdate(); 101 } catch (ClassNotFoundException e) { 102 // TODO Auto-generated catch block 103 e.printStackTrace(); 104 } catch (SQLException e) { 105 // TODO Auto-generated catch block 106 e.printStackTrace(); 107 } 108 try { 109 statement.close(); 110 connection.close(); 111 } catch (SQLException e) { 112 // TODO Auto-generated catch block 113 e.printStackTrace(); 114 } 115 116 } 117 118 // 删除操作 119 @Test 120 public void delete() { 121 Connection connection = null; 122 PreparedStatement prepareStatement = null; 123 try { 124 Class.forName("com.mysql.jdbc.Driver"); 125 connection = DriverManager.getConnection( 126 "jdbc:mysql://localhost:3306/day01", "root", "root"); 127 String sql = "delete from user where id=?"; 128 prepareStatement = connection.prepareStatement(sql); 129 prepareStatement.setInt(1, 5); 130 int i = prepareStatement.executeUpdate(); 131 if (i == 1) { 132 System.out.println("OK"); 133 } 134 } catch (ClassNotFoundException e) { 135 // TODO Auto-generated catch block 136 e.printStackTrace(); 137 } catch (SQLException e) { 138 // TODO Auto-generated catch block 139 e.printStackTrace(); 140 } 141 142 try { 143 prepareStatement.close(); 144 connection.close(); 145 } catch (SQLException e) { 146 // TODO Auto-generated catch block 147 e.printStackTrace(); 148 } 149 150 } 151 }
JavaEE学习之jdbc基础认识
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