SELECT t.group_id, (@item_id := @item_id + 1), t.item_name, t.item_number FROM ( SELECT group_id, item_name, item_number FROM some_table ORDER BY group_id ) t GROUP BY t.group_id;这个报错some_table不存在

这个错误提示表名 "some_table" 不存在。这个错误通常是由于以下原因之一引起的：

1. 表名输入错误：请检查表名是否正确，并确保没有拼写错误或语法错误。

2. 数据库中不存在该表：请确保您正在连接到正确的数据库，并检查该表是否存在。

3. 命名空间问题：某些数据库需要在表名前面添加命名空间。请检查您的数据库是否需要这样做。

请您仔细检查上述原因，找到错误的根源并进行修复。

相关问题

SELECT count( 0 ) FROM ( SELECT so.inventory_id AS dealUserId, so.inventory_name AS handlers, count( 0 ) AS secondNum, ( SELECT count( 0 ) FROM t_order_repair_item WHERE inventory_id = so.inventory_id ) AS totalCount FROM t_sub_order a LEFT JOIN t_order_repair_item so ON so.sub_order_id = a.sub_order_id WHERE a.repair_repeat = 1 AND so.inventory_id IS NOT NULL AND a.sls_name IN ( SELECT sls_name FROM t_sls_name WHERE sls_model_id IN ( 13, 14, 15 ) AND state = 0 AND del_flag = 0 ) GROUP BY so.inventory_id ) t 优化这条sql

这条SQL语句的性能瓶颈可能在于子查询和GROUP BY操作。以下是一些优化建议：

1. 避免使用子查询，可以使用JOIN操作代替。例如：

SELECT so.inventory_id AS dealUserId, so.inventory_name AS handlers, 
COUNT(0) AS secondNum, COUNT(DISTINCT sri.repair_item_id) AS totalCount
FROM t_sub_order a
LEFT JOIN t_order_repair_item so ON so.sub_order_id = a.sub_order_id
LEFT JOIN t_order_repair_item sri ON sri.inventory_id = so.inventory_id
JOIN t_sls_name sn ON a.sls_name = sn.sls_name
WHERE a.repair_repeat = 1
AND so.inventory_id IS NOT NULL
AND sn.sls_model_id IN (13, 14, 15)
AND sn.state = 0 AND sn.del_flag = 0
GROUP BY so.inventory_id, so.inventory_name;

2. 尽量避免使用函数，例如COUNT(0)可以写成COUNT(*)，可以提高性能。

3. 考虑创建适当的索引以加快查询速度。在这种情况下，可以考虑创建以下索引：

t_sub_order(repair_repeat, sls_name)
t_order_repair_item(sub_order_id, inventory_id)
t_order_repair_item(inventory_id)
t_sls_name(sls_name, sls_model_id, state, del_flag)

通过这些优化，应该能够提高查询性能。

优化 SELECT a.item_id, a.item_code, a.item_name, GROUP_CONCAT(b.channel_class_code) channelClassCodes, (SELECT count(*) FROM `tb_user_collection` where user_id = #{skuGoodDto.userId} and target_id = a.item_code) AS isCollect FROM osy_item AS a LEFT JOIN osy_item_sale AS b ON a.item_id = b.item_id where a.usable = 2 and b.usable = 2 and (b.channel_class_code = 10 or b.channel_class_code = 22) GROUP BY a.item_id

根据您提供的 SQL 查询语句，可以对其进行一些优化。首先，可以使用 IN 关键字来简化 WHERE 子句中的多个条件判断，将

(b.channel_class_code = 10 or b.channel_class_code = 22)

修改为

b.channel_class_code IN (10, 22)

接下来，可以使用 LEFT JOIN 连接 osy_item 和 osy_item_sale 表，然后再使用 GROUP BY 子句对结果进行分组。这样可以避免在 SELECT 子查询中使用子查询。

下面是优化后的 SQL 查询语句：

SELECT a.item_id,
       a.item_code,
       a.item_name,
       GROUP_CONCAT(b.channel_class_code) AS channelClassCodes,
       COUNT(c.target_id) AS isCollect
FROM osy_item AS a
LEFT JOIN osy_item_sale AS b ON a.item_id = b.item_id
LEFT JOIN tb_user_collection AS c ON c.target_id = a.item_code AND c.user_id = #{skuGoodDto.userId}
WHERE a.usable = 2
      AND b.usable = 2
      AND b.channel_class_code IN (10, 22)
GROUP BY a.item_id;

请注意，上述 SQL 查询语句中的 `#{skuGoodDto.userId}` 是占位符，您需要根据实际情况将其替换为相应的用户 ID 值。