Question

我想更新表格但需要按商店名称分组。我希望所有具有相同商店名称的分组条目都使用相同的ID进行更新。所有其他商店都应该有自己的身份证。

这就是我的尝试：

SET @row_number:=0;

UPDATE `TABLE 75` as t1
INNER JOIN (SELECT search_shop FROM `TABLE 75` WHERE sap_id = '' GROUP BY search_shop) as t2
ON t1.search_shop = t2.search_shop
SET sap_id = CONCAT('XX',@row_number:=@row_number+1)

使用此查询，每个条目都获得一个自己的ID - 即使是具有相同名称的ID。

所以我想要这样的事情：

shop_name - sap_id
sm_name_1 - XX1
sm_name_2 - XX2
sm_name_2 - XX2
sm_name_3 - XX3

等等。

提前感谢您的帮助！：）

Answer 1

CREATE TABLE t
    (`shop_name` varchar(9), `sap_id` varchar(3))
;

INSERT INTO t
    (`shop_name`, `sap_id`)
VALUES
    ('sm_name_1', ''),
    ('sm_name_2', 'XX2'),
    ('sm_name_2', ''),
    ('sm_name_3', 'XX3'),
    ('sm_name_3', ''),
    ('sm_name_4', ''),
    ('sm_name_5', '')
;

update t
inner join (
  select
  t.shop_name
  , CONCAT('XX', @rn := if(@prev = shop_name, @rn, @rn + 1)) as sap_id
  , @prev := shop_name
  from
  t
  , (select @prev := null, @rn := 0) var_init
  order by shop_name
)sq on t.shop_name = sq.shop_name
set t.sap_id = sq.sap_id;

select * from t;

| SHOP_NAME | SAP_ID |
|-----------|--------|
| sm_name_1 |    XX1 |
| sm_name_2 |    XX2 |
| sm_name_2 |    XX2 |
| sm_name_3 |    XX3 |
| sm_name_3 |    XX3 |
| sm_name_4 |    XX4 |
| sm_name_5 |    XX5 |

在sqlfiddle demo

使用group by和variable更新MySQL

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