数据库每条数据有商户id字段、数量number字段、时间createtime字段 现在要查询近七日每个商户的number总数 根据日期分组 mysql和java实现代码

MySQL查询语句如下：

SELECT 
    merchant_id, 
    DATE_FORMAT(createtime, '%Y-%m-%d') as date, 
    SUM(number) as total_number
FROM 
    your_table_name
WHERE 
    createtime >= DATE_SUB(CURDATE(), INTERVAL 7 DAY)
GROUP BY 
    merchant_id, date;

上面的查询语句会返回每个商户在过去七天内每天的number总数。

Java代码实现如下：

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Date;
import java.util.List;

public class TotalNumberByMerchant {
    public static void main(String[] args) {
        String url = "jdbc:mysql://localhost:3306/your_database_name";
        String user = "your_username";
        String password = "your_password";

        try (Connection conn = DriverManager.getConnection(url, user, password)) {
            String sql = "SELECT merchant_id, DATE_FORMAT(createtime, '%Y-%m-%d') as date, SUM(number) as total_number "
                    + "FROM your_table_name "
                    + "WHERE createtime >= ? "
                    + "GROUP BY merchant_id, date";
            PreparedStatement pstmt = conn.prepareStatement(sql);
            Calendar cal = Calendar.getInstance();
            SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
            Date today = new Date();
            cal.setTime(today);
            cal.add(Calendar.DATE, -7);
            Date lastWeek = cal.getTime();
            pstmt.setString(1, sdf.format(lastWeek));
            ResultSet rs = pstmt.executeQuery();
            List<TotalNumberByMerchantDTO> list = new ArrayList<>();
            while (rs.next()) {
                TotalNumberByMerchantDTO dto = new TotalNumberByMerchantDTO();
                dto.setMerchantId(rs.getInt("merchant_id"));
                dto.setDate(rs.getString("date"));
                dto.setTotalNumber(rs.getInt("total_number"));
                list.add(dto);
            }
            System.out.println(list);
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

class TotalNumberByMerchantDTO {
    private int merchantId;
    private String date;
    private int totalNumber;

    public int getMerchantId() {
        return merchantId;
    }

    public void setMerchantId(int merchantId) {
        this.merchantId = merchantId;
    }

    public String getDate() {
        return date;
    }

    public void setDate(String date) {
        this.date = date;
    }

    public int getTotalNumber() {
        return totalNumber;
    }

    public void setTotalNumber(int totalNumber) {
        this.totalNumber = totalNumber;
    }

    @Override
    public String toString() {
        return "TotalNumberByMerchantDTO [merchantId=" + merchantId + ", date=" + date + ", totalNumber=" + totalNumber
                + "]";
    }
}

上面的Java代码会连接到MySQL数据库并执行上述查询语句，将结果封装成DTO并输出到控制台。请将代码中的`your_database_name`、`your_username`、`your_password`、`your_table_name`替换为实际的数据库名、用户名、密码和表名。