mysql插入中文出现乱码

-- 查看数据库字符集
SHOW CREATE DATABASE your_database_name;

-- 修改数据库字符集
ALTER DATABASE your_database_name CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;

-- 查看表字符集
SHOW CREATE TABLE your_table_name;

-- 修改表字符集
ALTER TABLE your_table_name CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;

-- 修改列字符集
ALTER TABLE your_table_name MODIFY your_column_name VARCHAR(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;

jdbc:mysql://localhost:3306/your_database_name?useUnicode=yes&characterEncoding=UTF-8

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;

public class MySQLInsertExample {
    public static void main(String[] args) {
        String url = "jdbc:mysql://localhost:3306/your_database_name?useUnicode=yes&characterEncoding=UTF-8";
        String user = "your_username";
        String password = "your_password";

        try (Connection conn = DriverManager.getConnection(url, user, password)) {
            String sql = "INSERT INTO your_table_name (your_column_name) VALUES (?)";
            try (PreparedStatement pstmt = conn.prepareStatement(sql)) {
                pstmt.setString(1, "你好，世界！");
                pstmt.executeUpdate();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}