SQL 根据同一列中的其他值更新列

Question

我有一个 table 与此类似：

Index    Name       Type
--------------------------------
1        'Apple'   'Fruit'
2        'Carrot'  'Vegetable'
3        'Orange'  'Fruit'
3        'Mango'   'Fruit'
4        'Potato'  'Vegetable'

并想将其更改为：

Index    Name       Type
--------------------------------
1        'Apple'   'Fruit 1'
2        'Carrot'  'Vegetable 1'
3        'Orange'  'Fruit 2'
3        'Mango'   'Fruit 3'
4        'Potato'  'Vegetable 2'

是否有机会在智能更新查询中执行此操作（= 没有游标）？

Answer 1

您可以运行 update 和 join 得到 row_number() 每行的 [type] 组，然后将这些值与 [type] 使用 [index] 作为粘合列：

update t1 set t1.[type] = t1.[type] + ' ' + cast(t2.[rn] as varchar(3))
from [tbl] t1
join ( select [index]
            , row_number() over (partition by [type] order by [index]) as [rn]
       from [tbl]
     ) t2 on t1.[index] = t2.[index]

SQLFiddle

Answer 2

假设您的 table 有一个名为 ID 的主键，那么您可以运行以下内容：

update fruits
set Type = newType
from
(
select f.id
       ,f.[index] 
       ,f.Name 
       ,f.[Type] 
       ,Type + ' '+ cast((select COUNT(*) 
                          from fruits 
                          where Type = f.Type 
                          and Fruits.id <= f.id) as varchar(10)) as newType
    from fruits f
) t
where t.id = fruits.id

Answer 3

SELECT Index ,Name, Type, ROW_NUMBER() OVER (PARTITION BY Type ORDER BY Index)AS RowNum
INTO #temp
FROM table_name

UPDATE #temp
SET Type = Type + ' ' + CAST(RowNum AS NVARCHAR(15))

UPDATE table_name
SET Type = t2.Type
FROM table_name t1
JOIN #temp t2 ON t2.Index = t1.Index

Answer 4

您可以使用可以更新 cte 的事实：

with cte as(select type, row_number() over(partition by type order by index) rn from table)
update cte set type = type + ' ' + cast(rn as varchar(10))

SQL 根据同一列中的其他值更新列

SQL update column depending on other values in same column

sql

sql-server

sql-server-2014