五月二十三日jdbc基础知识点

1.建立与数据库的连接
1.1导入jdbc包
1.2加载JDBC驱动
java.lang.Class.forName(JDBCDriverClass);
Class.forName(driver);
MySQL的加载驱动
Class.forName(com.mysql.jdbc.Driver);
1.3获取数据库连接对象
Connection conn = DriverManager.getConnection(url,user,password);
2执行SQL语句
步骤一：创建Statement对象
步骤二：调用Statement对象相应方法将Sql语句发送到所连接数据库
2.1创建执行对象
Statement stmt = conn.createStatement();
2.2执行查询语句：
public ResultSet executeQuery(String selectSql)
ResultSet rs = stmt.executeQuery(selectSql);
2.3 执行增删改语句：
public ResultSet executeUpdate(String updateSql);
Result rs = stmt.executeUpdate(updateSql);
3.处理返回结果
while(rs.next()){
String no = rs.getString("sNo");
String name = rs.getString("sName");
String sex = rs.getString("sex");
Int age = rs.getInt("age");
String dept = rs.getString("dept");
String address = rs.getString("address");
System.out.println(no+"\t"+name+"\t"+sex+"\t"+age+"\t"+dept+"\t"+address));
};
4.关闭创建的各种对象
步骤1：关闭结果集对象rs
步骤2：关闭执行对象stmt
步骤3：关闭数据库连接对象conn
try{
if(rs!=null) rs.close();
if(stmt!=null) stmt.close();
if(conn!=null) conn.close();}
catch(Exeption e){e.printStackTrace();}

 public   class   app17_15 {
      private   static  String driver = "com.mysql.jdbc.Driver" ;
      private   static  String url = "jdbc:mysql://localhost:3306/ku" ;
      private   static  String user = "root" ;
      private   static  String password = "root" ;
      public   static   void   main(String[] args) {
        String sql  = "SELECT sNo,sName,sex,age,dept,address FROM student WHERE dept = ‘计算机‘" ;
          try  (
                  //  创建数据库连接 
                Connection conn=  DriverManager.getConnection(url,user,password);
                  //  执行SQL语句 
                Statement stmt =  conn.createStatement();
                  //  处理返回结果 
                ResultSet rs =  stmt.executeQuery(sql);
                ){
            Class.forName(driver);  //  加载MySQL的驱动 
             while  (rs.next()){
                String no  = rs.getString("sNo" );
                String name  = rs.getString("sName" );
                String sex  = rs.getString("sex" );
                  int  age = rs.getInt("age" );
                String dept  = rs.getString("dept" );
                String address  = rs.getString("address" );
                System.out.println(no +"\t"+name+"\t"+sex+"\t"+age+"\t"+dept+"\t"+ address);
            }
        }
                  catch   (Exception e){
            e.printStackTrace();
                }
    }
} 

 

5.jdbc中三种SQL对表查询方式
第一种：Statement接口执行不带参数的静态SQL语句查询
静态SQL语句指执行executeQuery()以及executeUpdate()方法时，
SQL语句没有参数
第二种：PreparedStatement接口执行动态SQL语句查询
第三种：CallableStatement接口执行存储过程调用

 

 public   class   app17_16 {
      private   static  String driver = "com.mysql.jdbc.Driver" ;
      private   static  String url = "jdbc:mysql://localhost:3306/ku" ;
      private   static  String user = "root" ;
      private   static  String password = "root" ;
      public   static   void   main(String[] args) {
        String selectSql  = "SELECT * FROM student WHERE dept = ‘计算机‘" ;
        String insertSql  = "INSERT INTO student(sNo,sName,sex,age,dept,address) VALUES(‘9‘,‘刘六‘,‘女‘,22,‘外语‘,‘湖南‘)" ;
        String updateSql  = "UPDATE student SET dept =‘金融‘ WHERE sNo = ‘7‘" ;
        String deleteSql  = "DELETE FROM student WHERE sNo = ‘3‘" ;
          try  (
                Connection conn   =  DriverManager.getConnection(url,user,password);
                Statement stmt  =  conn.createStatement();
                ResultSet rs  =  stmt.executeQuery(selectSql);
                ){
            Class.forName(driver);
              while  (rs.next()) {
                String no  = rs.getString("sNo" );
                String name  = rs.getString("sName" );
                String sex  = rs.getString("sex" );
                  int  age = rs.getInt("age" );
                String dept  = rs.getString("dept" );
                String address  = rs.getString("address" );
                System.out.println(no  + "\t" + name + "\t" + sex + "\t" + age + "\t" + dept + "\t" +  address);
            }
            {
                  int  count =  stmt.executeUpdate(insertSql);
                System.out.println( "添加了"+count+"记录到student表" );
                count  =  stmt.executeUpdate(updateSql);
                System.out.println( "修改了"+count+"记录到student表" );
                count  =  stmt.executeUpdate(deleteSql);
                System.out.println( "删除了"+count+"记录到student表" );
            }
        }
                  catch   (Exception e){
            e.printStackTrace();
                }
    }
} 

 

总结：熟悉了一遍数据库与idea的连接

创建数据库连接对象

创建SQL执行对象

处理返回结果集

关闭对象

令我耗时的是程序出来咯，但由于没有导入jar包，导致出错

 

五月二十三日jdbc基础知识点

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