SELECT * FROM redeem_code WHERE serverId='nobody_dev' AND redeemType='1' ORDER BY batch ASC;如何每个batch都只返回一条数据

上述SQL语句已经按照`batch`字段升序排列了(`ORDER BY batch ASC`)，如果每个`batch`只想返回一条数据，那么你需要使用一种称为“分组”的技术来保证。但是，由于`SELECT *`会选取所有列，如果一个`batch`中有多个满足条件的行，它会全部返回。如果你只需要每个`batch`的一条代表数据，可以考虑使用`LIMIT`或者`OFFSET`配合`ROW_NUMBER()`。

这里有一个示例，使用`ROW_NUMBER()`来指定每个组的第一行：

WITH ranked_codes AS (
    SELECT *, ROW_NUMBER() OVER (PARTITION BY batch ORDER BY created_at) as rn
    FROM redeem_code
    WHERE serverId = 'nobody_dev' AND redeemType = '1'
)
SELECT * FROM ranked_codes
WHERE rn = 1;

这将返回每个`batch`中的第一行，也就是最早的那一条。

相关问题

SELECT a.goods_code goodsCode, a.goods_name goodsName, a.goods_price goodsPrice, a.original_price originalPrice, IFNULL( a.initial_sales, 0 )+ IFNULL( a.real_sales, 0 ) sales, a.thumbnail, CASE WHEN a.exchange_type IS NULL OR a.exchange_type = 0 THEN '不限制' ELSE a.exchange_number END exchangeTypeName, (SELECT MIN(b.redeem_points) redeem_points FROM goods_attr_info b WHERE a.goods_code = b.goods_code ) redeem_points, CASE WHEN (SELECT MIN(b.inventory_number) <= 10 FROM goods_attr_info b WHERE a.goods_code = b.goods_code AND b.inventory_type = 1) THEN CONCAT('剩余',MIN(b.inventory_number),'件') ELSE '' END inventoryNumber FROM goods_main_info a WHERE a.goods_status = 1 这断sql改造成上述语句

可以使用以下 SQL 语句实现：

SELECT a.goods_code AS goodsCode,
       a.goods_name AS goodsName,
       a.goods_price AS goodsPrice,
       a.original_price AS originalPrice,
       IFNULL(a.initial_sales, 0) + IFNULL(a.real_sales, 0) AS sales,
       a.thumbnail,
       CASE WHEN a.exchange_type IS NULL OR a.exchange_type = 0 THEN '不限制'
            ELSE a.exchange_number END AS exchangeTypeName,
       (SELECT MIN(b.redeem_points)
        FROM goods_attr_info b
        WHERE a.goods_code = b.goods_code) AS redeem_points,
       CASE WHEN (SELECT MIN(b.inventory_number)
                  FROM goods_attr_info b
                  WHERE a.goods_code = b.goods_code AND b.inventory_type = 1) <= 10
            THEN CONCAT('剩余', MIN(b.inventory_number), '件')
            ELSE '' END AS inventoryNumber
FROM goods_main_info a
WHERE a.goods_status = 1;

这个语句的逻辑与之前的语句相同，只是将子查询部分的逻辑拆分出来，分别使用了两个子查询来计算 `redeem_points` 和 `inventoryNumber`，并且使用了 `CASE WHEN` 语句来判断是否需要输出 `inventoryNumber`。

for i,row in test_offline.iterrows()在python中用该语句添加从2014901到2014931的report_date total_purchase_amt total_redeem_amt

在Python的pandas库中，`for i, row in test_offline.iterrows()`是一个常见的用于迭代DataFrame行的循环结构。当你想对DataFrame `test_offline` 中每个包含`report_date`, `total_purchase_amt` 和 `total_redeem_amt` 列的行执行特定操作时，你可以这样做：

# 假设test_offline是一个已存在的DataFrame
start_date = 2014901
end_date = 2014931

# 首先，检查日期范围内的数据是否已在DataFrame内
if start_date <= test_offline['report_date'].min() or end_date >= test_offline['report_date'].max():
    print("部分日期超出了DataFrame的报告日期范围")

else:
    # 使用条件判断并更新指定行的数据
    for i, row in test_offline.loc[(test_offline['report_date'] >= start_date) & (test_offline['report_date'] <= end_date)].iterrows():
        # 这里假设total_purchase_amt和total_redeem_amt需要加上新的值
        # 新增的值可以赋给row['total_purchase_amt']和row['total_redeem_amt']
        row['total_purchase_amt'] += 新购金额 # 你需要提供具体的数值
        row['total_redeem_amt'] += 新赎回金额 # 同样提供具体的数值
        
        # 更新后的行可以保存回原始DataFrame，如：
        test_offline.at[i, ['total_purchase_amt', 'total_redeem_amt']] = row[['total_purchase_amt', 'total_redeem_amt']]