设置行的递增和重置值

Question

我正在向现有表添加新的int列。我正在尝试为表中的所有行设置一个值。

players_table:
 - id
 - company_id
 - rank // new column

要设置等级的初始值，我只想按公司分组将等级增加1。

示例

companies:
id | name
---------------
1  | first comp
2  | second comp

players:
id | company_id | rank 
-----------------------
1  |     1      |   1
2  |     1      |   2
3  |     1      |   3
4  |     2      |   1
5  |     2      |   2

是否可以使用SQL来实现？

Answer 1

您可以使用public static class GlobalClass { public static string myGlobal=""; } class myClass { string myClassVariable = ""; private void method() { //myGlobal is accessible using this GlobalClass.myGlobal ="some value"; //myClassVariable is accessible here myClassVariable = "somevalue"; if(condition) { //myClassVariable is also accessible here myClassVariable = "somevalue"; string ifBlockVariable = ""; } //ifBlockVariable is not accessible here } } ：

row_number()

要设置值，请使用select p.*, row_number() over (partition by p.company_id order by p.id) as rank from players p; ：

update

Answer 2

您可以尝试使用ROW_NUMBER或RANK窗口功能。

SELECT *,ROW_NUMBER() OVER(PARTITION BY company_id order by id )rank
FROM players