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 如果数据不满7天 需补齐剩余日期数据 mysql java spring boot、

MySQL查询语句如下：

SELECT 
    merchant_id, 
    DATE_FORMAT(date, '%Y-%m-%d') as date, 
    COALESCE(SUM(number), 0) as total_number
FROM (
    SELECT 
        merchant_id, 
        DATE(c.createtime) as date, 
        0 as number
    FROM 
        (SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7) d
    LEFT JOIN 
        (SELECT DISTINCT merchant_id FROM your_table_name) m 
    ON 1=1
    LEFT JOIN 
        your_table_name c 
    ON 
        m.merchant_id=c.merchant_id AND DATE(c.createtime) = DATE_SUB(CURRENT_DATE, INTERVAL d.d DAY)
    WHERE 
        d.d BETWEEN 0 AND 6
    UNION ALL
    SELECT 
        merchant_id, 
        DATE(c.createtime) as date, 
        SUM(number) as number
    FROM 
        your_table_name c
    WHERE 
        c.createtime >= DATE_SUB(CURRENT_DATE, INTERVAL 6 DAY)
    GROUP BY 
        merchant_id, DATE(c.createtime)
) t
GROUP BY 
    merchant_id, date
ORDER 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，如果数据不满7天，会自动补齐剩余日期的数据。

Java Spring Boot代码实现如下：

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Service;

import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Date;
import java.util.List;
import java.util.Map;

@Service
public class TotalNumberByMerchantService {
    @Autowired
    private JdbcTemplate jdbcTemplate;

    public List<TotalNumberByMerchantDTO> getTotalNumberByMerchant() {
        String sql = "SELECT merchant_id, DATE_FORMAT(date, '%Y-%m-%d') as date, COALESCE(SUM(number), 0) as total_number "
                + "FROM ( "
                + "    SELECT merchant_id, DATE(c.createtime) as date, 0 as number "
                + "    FROM (SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7) d "
                + "    LEFT JOIN (SELECT DISTINCT merchant_id FROM your_table_name) m ON 1=1 "
                + "    LEFT JOIN your_table_name c ON m.merchant_id=c.merchant_id AND DATE(c.createtime) = DATE_SUB(CURRENT_DATE, INTERVAL d.d DAY) "
                + "    WHERE d.d BETWEEN 0 AND 6 "
                + "    UNION ALL "
                + "    SELECT merchant_id, DATE(c.createtime) as date, SUM(number) as number "
                + "    FROM your_table_name c "
                + "    WHERE c.createtime >= DATE_SUB(CURRENT_DATE, INTERVAL 6 DAY) "
                + "    GROUP BY merchant_id, DATE(c.createtime) "
                + ") t "
                + "GROUP BY merchant_id, date "
                + "ORDER BY merchant_id, date";
        List<Map<String, Object>> rows = jdbcTemplate.queryForList(sql);
        List<TotalNumberByMerchantDTO> list = new ArrayList<>();
        for (Map<String, Object> row : rows) {
            TotalNumberByMerchantDTO dto = new TotalNumberByMerchantDTO();
            dto.setMerchantId((int) row.get("merchant_id"));
            dto.setDate((String) row.get("date"));
            dto.setTotalNumber((int) row.get("total_number"));
            list.add(dto);
        }
        return list;
    }

    public static void main(String[] args) {
        TotalNumberByMerchantService service = new TotalNumberByMerchantService();
        List<TotalNumberByMerchantDTO> list = service.getTotalNumberByMerchant();
        System.out.println(list);
    }
}

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代码使用了Spring Boot的JdbcTemplate来连接到MySQL数据库并执行上述查询语句，将结果封装成DTO并返回。请将代码中的`your_table_name`替换为实际的表名。