「java更改mysql」java更改jdk版本
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本文目录一览：
- 1、java修改MySQL表中的数据问题：如代码
- 2、如何在java中修改MySQL表中的数据，下面代码不对。求帮忙
- 3、java程序操作MySQL数据库
- 4、如何用java实现对mysql进行增删改查
java修改MySQL表中的数据问题：如代码
你的代码写的很乱。
首先if (jpf3.equals(jpf2)) {
if (jpf1.equals(mima)) {
String str="update 人员信息表 set 密码 = '001' where 人员编号 = '001'; ";
//（如果这句换成： String str="update 人员信息表 set 密码 = 'jpf3' where 人员编号 = 'jtf1'; ";就不会修改成功。 为什么啊？ 求高人啊！正确格式是什么呢？
）
Statement statement =con.createStatement();
int s=statement.executeUpdate(str);
JOptionPane.showMessageDialog(null, "修改成功");
这一部分是要写在try{}里面的，finally{}里面要对PreparedStatement进行判断，要关闭。
你的sql语句里面使用的是变量
如果变量是String类型的： String str="update 人员信息表 set 密码 = '"+jpf3+"' where 人员编号 = '"+jtf1+"';
如果是int,long，double之类的：String str="update 人员信息表 set 密码 = "+jpf3+" where 人员编号 = "+jtf1+";
如何在java中修改MySQL表中的数据，下面代码不对。求帮忙
update user set name=?,sex=?,birthday=? where id=? 中有四个问号( 也就是占位符)，但是prept只绑定了三次值。第四个占位符没绑定
java程序操作MySQL数据库
数据库内容
java源代码 （代码实现的是查询成绩为 的人员信息 至于其他功能的 代码中有注释） 注意 在eclipse里运行程序的时候 要工程里插入jar包 否则运行异常！ import java sql *; import java io *; class database_manage { public Connection conn = null; public ResultSet rs = null; private String DatabaseDriver = " mysql jdbc Driver"; // DataSource 数据源名称DSN private String DatabaseConnStr = "jdbc:mysql://localhost: /people_manage?useUnicode=truecharacterEncoding=utf " + " root root"; public void setDatabaseDriver(String Driver) { this DatabaseDriver = Driver; } public String getDatabaseDriver() { return (this DatabaseDriver); } public void setDatabaseConnStr(String ConnStr) { this DatabaseConnStr = ConnStr; } public String getDatabaseConnStr() { return (this DatabaseConnStr); } public database_manage() {// 构造函数连接数据库 try { Class forName(DatabaseDriver); } catch (java lang ClassNotFoundException e) { System err println("加载驱动器有错误:" + e getMessage()); System out print("执行插入有错误:" + e getMessage());// 输出到客户端 } } public ResultSet query(String sql) {// 查询数据库 rs = null; try { conn = DriverManager getConnection( "jdbc:mysql://localhost: /people_manage?useUnicode=truecharacterEncoding=utf " "root" "root"); Statement stmt = conn createStatement(); rs = stmt executeQuery(sql); } catch (SQLException ex) { System err println("执行查询有错误:" + ex getMessage()); System out print("执行查询有错误:" + ex getMessage()); // 输出到客户端 }
return rs;
} public int update_database(String sql) {// 更新或插入数据库 int num = ; try { conn = DriverManager getConnection( "jdbc:mysql://localhost: /people_manage?useUnicode=truecharacterEncoding=utf " "root" "root"); Statement stmt = conn createStatement(); num = stmt executeUpdate(sql); } catch (SQLException ex) { System err println("执行插入有错误:" + ex getMessage()); System out print("执行插入有错误:" + ex getMessage());// 输出到客户端 } CloseDataBase(); return num; } public void CloseDataBase() {// 关闭数据库 try { conn close(); } catch (Exception end) { System err println("执行关闭Connection对象有错误 " + end getMessage()); System out print("执行执行关闭Connection对象有错误 有错误:" + end getMessage()); // 输出到客户端 } } } class people { private String uid; private String name; private String banji; private int score; public people() { } public people(String uid String name String banji) { this uid = uid; this name = name; this banji = banji; } public people(String uid String name String banji int score) { this uid = uid; this name = name; this banji = banji; this score = score; } public String getUid() { return uid; } public void setUid(String uid) { this uid = uid; } public String getName() { return name; } public void setName(String name) { this name = name; } public String getBanji() { return banji; } public void setBanji(String banji) { this banji = banji; } public int getScore() { return score; } public void setScore(int score) { this score = score; } } public class manage { private people[] people_array ;// 对象数组 public void add_people(String uid String name) { String sql = "insert people (uid name) values ( " + uid + " " + name + " )";// sql插入语句 // String sql = "insert people (uid name) values ( uid tom )"; database_manage db_obj = new database_manage(); db_obj update_database(sql); } public void update_people(String uid String name) { String sql = "update people set name= " + name + " where uid= " + uid + " "; database_manage db_obj = new database_manage(); db_obj update_database(sql); } public void delete_people(String uid) { String sql = "delete from people where uid= " + uid + " "; database_manage db_obj = new database_manage(); db_obj update_database(sql); } public people query_people(String uid) { database_manage db_obj = new database_manage(); // String adminid=null; String uid_new name banji; uid_new = null; name = null; banji = null; String sql_query = "select * from people where uid= " + uid + " "; try { ResultSet rs = db_obj query(sql_query); if (rs next()) { uid_new = rs getString("uid"); name = rs getString("name"); banji = rs getString("banji"); } } catch (Exception e) { e getMessage(); } people new_people = new people(uid_new name banji); return new_people; } public people[] query_people_byscore(int score) { database_manage db_obj = new database_manage(); String uid_new name banji; uid_new = null; name = null; banji = null; int score_new = ;
String sql_query = "select * from people where score=" + score;// sql查询语句
try {
ResultSet rs = db_obj query(sql_query);// 查询后 返回结果集
int num = ;
ResultSet rs_new = rs;
while (rs_new next()) {// 统计结果集中学生个数
num++;
}
// System out println(num);
people_array = new people[num];
int i = ;
rs beforeFirst();// 返回结果集的开始
while (rs next()) {
uid_new = rs getString("uid");
name = rs getString("name");
banji = rs getString("banji");
score_new = rs getInt("score");
people_array [i] = new people(uid_new name banji score_new);
i++;
}
} catch (Exception e) {
e getMessage();
}
return people_array ;
}
public static void main(String args[]) {
/*
* people new_people=new people();
*
* manage mr=new manage(); //mr add_people(" " "小明");插入一个学生的信息
*
* new_people=mr query_people(" ");//查询uid= 的学生信息 返回对象 System out
* println(""+new_people getName()+" "+new_people getBanji());
* mr update_people(" " "小王");更新一个学生的信息
*
* new_people=mr query_people(" ");//更新后查询
*
* System out println(""+new_people getName()+" "+new_people getBanji(
* ));
*/
manage mr = new manage();
// mr delete_people(" ");删除uid= 的学生信息
people[] people_array;// 声明对象数组
people_array = mr query_people_byscore( );// 返回成绩为一百的学生类数组 后输出
int num = ;
num = people_array length;
for (int i = ; i num; i++) {
System out println(people_array[i] getUid() + " "
+ people_array[i] getName() + " "
+ people_array[i] getBanji() + " "
+ people_array[i] getScore());
}
}
}
lishixinzhi/Article/program/Java/JSP/201311/20030
如何用java实现对mysql进行增删改查
jdbc。。首先你的下载mysql然后下载jdbc驱动，然后在你的代码里与数据库连接，连接成功后就可以在代码里用sql语句对mysql实现增删改查了
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