JDBC鏈接mysql插入數據后顯示問號的原因及解決辦法

2024-07-24 12:45:01

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1.在cmd中進入mysql查看默認的編碼格式:

mysql> show variables like "%char%";

若不是utf8(因為我用的是utf8)，關掉mysql服務，在my.ini中添加

[client]default-character-set=utf8[mysqld]default-storage-engine=INNODBcharacter-set-server=utf8collation-server=utf8_general_ci[mysql]default-character-set=utf8

2.eclipse中的編碼格式是否為utf8

3.如果還是不可以，檢查mysql客戶端表格的編碼方式

show create table tablename

如果不是utf-8.刪掉重新建立一張表（之前我在原表上改動沒有成功，可能是我自己操作的原因）

分享一個經典的JDBC連接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"); //加載mysq驅動} catch (ClassNotFoundException e) {System.out.println("驅動加載錯誤");e.printStackTrace();//打印出錯詳細信息}try {url = "jdbc:mysql://localhost/test?user=root&password=yqs2602555&useUnicode=true&&characterEncoding=gb2312&autoReconnect = true";//簡單寫法：url = "jdbc:myqsl://localhost/test(數據庫名)? user=root(用戶)&password=yqs2602555(密碼)";user = "root";password = "yqs2602555";conn = DriverManager.getConnection(url,user,password);} catch (SQLException e) {System.out.println("數據庫鏈接錯誤");e.printStackTrace();}try {stmt = conn.createStatement();sql = "select * from dept";//dept這張表有deptno，deptname和age這三個字段rs = stmt.executeQuery(sql);//執行sql語句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("數據操作錯誤");e.printStackTrace();}//關閉數據庫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("數據庫關閉錯誤");e.printStackTrace();}}}

運行結果如下：

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