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JDBC链接mysql插入数据后显示问号的原因及解决办法_MySQL

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2018-05-18 10:51:253010browse

1.在cmd中进入mysql查看默认的编码格式:

mysql> show variables like "%char%";

若不是utf8(因为我用的是utf8),关掉mysql服务,在my.ini中添加

[client]
default-character-set=utf8
[mysqld]
default-storage-engine=INNODB
character-set-server=utf8
collation-server=utf8_general_ci
[mysql]
default-character-set=utf8

2.eclipse中的编码格式是否为utf8

3.如果还是不可以,检查mysql客户端表格的编码方式

show create table tablename

如果不是utf-8.删掉重新建立一张表(之前我在原表上改动没有成功,可能是我自己操作的原因)

分享一个经典的JDBC连接MySQL的程序

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class MySQLConnection {
public static void main(String[] args) {
Connection conn = null;
Statement stmt = null;
ResultSet rs = null;
String url = null;
String user = null;
String password = null;
String sql = null;
try {
Class.forName("com.mysql.jdbc.Driver"); //加载mysq驱动
} catch (ClassNotFoundException e) {
System.out.println("驱动加载错误");
e.printStackTrace();//打印出错详细信息
}
try {
url = 
"jdbc:mysql://localhost/test?user=root&password=yqs2602555
&useUnicode=true&&
characterEncoding=gb2312&autoReconnect = true";
//简单写法:url = "jdbc:myqsl://localhost/test(数据库名)? user=root(用户)&password=yqs2602555(密码)";
user = "root";
password = "yqs2602555";
conn = DriverManager.getConnection(url,user,password);
} catch (SQLException e) {
System.out.println("数据库链接错误");
e.printStackTrace();
}
try {
stmt = conn.createStatement();
sql = "select * from dept";//dept这张表有deptno,deptname和age这三个字段
rs = stmt.executeQuery(sql);//执行sql语句
while(rs.next()) {
System.out.print(rs.getInt("deptno") + " ");
System.out.print(rs.getString("deptname") + " ");
System.out.println(rs.getInt("age") + " ");
}
} catch (SQLException e) {
System.out.println("数据操作错误");
e.printStackTrace();
}
//关闭数据库
try {
if(rs != null) {
rs.close();
rs = null;
}
if(stmt != null) {
stmt.close();
stmt = null;
}
if(conn != null) {
conn.close();
conn = null;
}
} catch(Exception e) {
System.out.println("数据库关闭错误");
e.printStackTrace();
}
}
}

运行结果如下:

1 yqs 0 
2 hello 0 
3 yqsshr 0 
4 world 0 
5 hryspa 0 
1 yqs 0 
2 hello 0 
3 yqsshr 0 
4 world 0 
5 hryspa 0 
1 yqs11 21 
1 yqs21 31 
1 yqs31 41 
1 yqs41 51

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