标签：system val 取数 cts values 删除 rgba rgs sele
Jdbc连接数据库
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
标签：system val 取数 cts values 删除 rgba rgs sele
原文地址：https://www.cnblogs.com/kzf-99/p/14806902.html
