sql表中2行的交换值

问题描述

| 我有一个表，其中有列名课程。第二行的课程是\“ C ++ \”，第四行的课程是\“ ASP.net \”。 我想将其与更新查询交换价值。我该如何实现？     

解决方法

您可以使用

update

更改值，例如：

update YourTable set Course = \'ASP.NET\' where id = 2
update YourTable set Course = \'C++\' where id = 4

要么：

update  YourTable 
set     Course = 
        case id
        when 2 then \'ASP.NET\'
        when 4 then \'C++\'
        end 
where   id in (2,4)

    ,测试表和数据

create table YourTable(id int primary key,course varchar(10))

insert into  YourTable values (1,\'Delphi\')
insert into  YourTable values (2,\'C++\')
insert into  YourTable values (3,\'Clipper\')
insert into  YourTable values (4,\'ASP.net\')

更新到开关2和4

update YourTable set
  course = case id
             when 4 then (select course from YourTable where id = 2)
             when 2 then (select course from YourTable where id = 4)
             else T.course
           end  
from
  YourTable as T
where T.id in (2,4)  

结果

id  course
1   Delphi
2   ASP.net
3   Clipper
4   C++